STATE OF THE WORLD's FORESTs 2003 Sustainable use and management of freshwater resources. the role of forests D spendable freshwater supplies and the Technologies exist to deal with water scarcity bility to cope with the extremes of too little and to some extent with the effects of or too much water are requisites for sustainable hydrometeorological extremes( Brooks et al human development. Warnings of freshwater 1997). If they are to be turned into solutions scarcity issued at the end of the twentieth century several constraints must be overcome, including (e. g Falkenmark, 1989; Kundzewicz, 1997; land scarcity and inadequate policies an Vorosmarty et aL., 2000)are proving to be accurate, institutions that hamper an effective response to the point that lack of water now threatens food( Kundzewicz, 1997; Rosegrant, 1997; Scherr and security, livelihoods and human health(see UN, Yadav, 1996). Although land use and freshwater 1992: IFPRL, 2001). Worldwide freshwater are inextricably linked, they are rarely managed supports about 40 percent of all food-crop in concert. Upstream uses of land and water can production via irrigation, supports 12 percent of affect downstream communities and their use all fish consumed by humans and generates 20 of water. The converse is also true. Such percent of all electric power ohnson, Revenga linkages are readily seen with a watershed vernia, 2001). In addition to the direct perspective, but are not always fully taken into impact of water scarcity, impaired quality of account when responses are being developed at water reduces its usabilit the local national and international levels More than 3 billion people worldwide do not The International Year of mountains -2002 have access to clean water, and the problem is (iNternet:www.mountains2002.org)focused particularly acute in developing countries, where worldwide attention on land and water use in 90 percent of wastewater is discharged into mountainous watersheds. As the headwaters streams without treatment (ohnson, Revenga and for all major rivers of the world, many of which Echeverria, 2001). Of the more than 3 million are or were at one time forested these deaths that are attributed to polluted water and watersheds are a key to freshwater poor sanitation annually, more than 2 million are management. The relationship between forests children in developing countries(van Damme, and freshwater, in both tropical and temperate 2001). Furthermore, extensive loss of life and regions, therefore needs to be understood if economic productivity result each year from rain- forests are to be better managed to sustain the induced landslides, floods and torrents in productivity of uplands without affecting developed and developing countries alike. Water humans and the soil and water on which they and its management are therefore strategically depend. Enhancing the chances of achieving important to economies and the well-being of such objectives means taking a watershed people, and water management has become one of management perspective in the planning, the major challenges of this century. Conflicts over monitoring and implementation of forest, water water use will arise as water becomes increasingly resource, agricultural and urban development scarce, making action on many fronts imperative. pr
2003 FORESTS S’WORLD THE OF STATE 74 and use Sustainable of management :resources freshwater forests of role the the and supplies freshwater Dependable little too of extremes the with cope to ability sustainable for requisites are water much too or freshwater of Warnings. development human century twentieth the of end the at issued scarcity ;1997, Kundzewicz; 1989, Falkenmark. g.e( ,accurate be to proving are) 2000., al et Vorosmarty food threatens now water of lack that point the to ,UN see (health human and livelihoods, security freshwater, Worldwide). 2001, IFPRI; 1992 crop-food all of percent 40 about supports of percent 12 supports, irrigation via production 20 generates and humans by consumed fish all Revenga, Johnson (power electric all of percent direct the to addition In). 2001, Echeverria and of quality impaired, scarcity water of impact .usability its reduces water not do worldwide people billion 3 than More is problem the and, water clean to access have where, countries developing in acute particularly into discharged is wastewater of percent 90 and Revenga, Johnson (treatment without streams million 3 than more the Of). 2001, Echeverria and water polluted to attributed are that deaths are million 2 than more, annually sanitation poor ,Damme van (countries developing in children and life of loss extensive, Furthermore). 2001 in torrents and floods, landslides inducedrain from year each result productivity economic Water. alike countries developing and developed strategically therefore are management its and of being-well the and economies to important of one become has management water and, people over Conflicts. century this of challenges major the increasingly becomes water as arise will use water .imperative fronts many on action making, scarce ,scarcity water with deal to exist Technologies of effects the with extent some to and ,.al et Brooks (extremes hydrometeorological ,solutions into turned be to are they If). 1997 including, overcome be must constraints several and policies inadequate and scarcity land response effective an hamper that institutions and Scherr; 1997, Rosegrant; 1997, Kundzewicz( freshwater and use land Although). 1996, Yadav managed rarely are they, linked inextricably are can water and land of uses Upstream. concert in use their and communities downstream affect Such. true also is converse The. water of watershed a with seen readily are linkages into taken fully always not are but, perspective at developed being are responses when account .levels international and national, local the 2002 – Mountains of Year International The focused) org.mountains2002.www: Internet( in use water and land on attention worldwide headwaters the As. watersheds mountainous which of many, world the of rivers major all for these, forested time one at were or are freshwater to key a are watersheds forests between relationship The. management temperate and tropical both in, freshwater and if understood be to needs therefore, regions the sustain to managed better be to are forests affecting without uplands of productivity they which on water and soil the and humans achieving of chances the Enhancing. depend watershed a taking means objectives such ,planning the in perspective management water, forest of implementation and monitoring development urban and agricultural, resource .programmes
PART II SELECTED CURRENT ISSUES IN THE FOREST SECTOR Forested mountain watersheds are a key to dependable freshwater supplies(Switzerland) The loss of forest cover and conversion to other land uses can adversely affect freshwater upplies and compound human disasters resulting from hydrometeorological extremes ons can be improved ar overall water resource management facilitated if forests are managed with hydrological objectives in mind. While not a panacea for resolving water issues, forests can provide tangible economic and environmental benefits. A watershed framework helps identify these benefits in both Forests are found where there are large provide the greatest soil stability and the quantities of water, normally where precipitation lowest levels of soil mass movement, gully is abundant or in riparia erosion and surface erosion: moisture is high. Perception of the influence of export the lowest levels of sediment forests on water led to the establishment of the downstream national forest system in the United States, as forest cover was considered necessary to sustain FORESTS, ATMOSPHERIC WATER AND river flow(Lee, 1980). Most forests were WATER YIELD subsequently found to use great amounts of The relationship among forests, atmospheric water, contrary to early thinking. The present moisture and water yield has long been chapter summarizes the impact of forests on controversial. Lee(1980)noted that the natural freshwater and suggests how forests and forest coincidence of forest cover and higher management can help achieve water resource precipitation is at least partly responsible for the management objectives popular notion that forests increase or attract Forested watersheds are exceptionally stable rain, which leads to the assumption that their hydrological systems. In contrast to other land removal would significantly diminish healthy forests: precipitation. Globally, this is not the case; the strongly influence the quantity of water removal of all forest cover would only reduce ielded from watersheds global precipitation by 1 to 2 percent at most discharge the highest quality of water; (Lee, 1980). Calder(1999a)further suggested that discharge lower storm flow peaks and deforestation has little effect on regional volumes for a en ll precipitation, although exceptions could occur in moderate variation in stream flow between basins where rainfall largely depends on the high and low flows during a year, ternally driven circulation patterns such as the
75 SECTOR FOREST THE IN ISSUES CURRENT SELECTED II PART to conversion and cover forest of loss The freshwater affect adversely can uses land other disasters human compound and supplies .extremes hydrometeorological from resulting and improved be can conditions Watershed if facilitated management resource water overall objectives hydrological with managed are forests water resolving for panacea a not While. mind in economic tangible provide can forests, issues watershed A. benefits environmental and both in benefits these identify helps framework .areas downstream and upstream large are there where found are Forests precipitation where normally, water of quantities soil where areas riparian in or abundant is of influence the of Perception. high is moisture the of establishment the to led water on forests as, States United the in system forest national sustain to necessary considered was cover forest were forests Most). 1980, Lee (flow river of amounts great use to found subsequently present The. thinking early to contrary, water on forests of impact the summarizes chapter forest and forests how suggests and freshwater resource water achieve help can management .objectives management stable exceptionally are watersheds Forested land other to contrast In. systems hydrological :forests healthy, uses water of quantity the influence strongly• ;watersheds from yielded ;water of quality highest the discharge• and peaks flow storm lower discharge• ;rainfall of input given a for volumes between flow stream in variation moderate• ;year a during flows low and high the the and stability soil greatest the provide• gully, movement mass soil of levels lowest ;erosion surface and erosion sediment of levels lowest the export• .downstream AND WATER ATMOSPHERIC, FORESTS YIELD WATER atmospheric, forests among relationship The been long has yield water and moisture natural the that noted) 1980 (Lee. controversial higher and cover forest of coincidence the for responsible partly least at is precipitation attract or increase forests that notion popular their that assumption the to leads which, rain diminish significantly would removal the; case the not is this, Globally. precipitation reduce only would cover forest all of removal most at percent 2 to 1 by precipitation global that suggested further) 1999a (Calder). 1980, Lee( regional on effect little has deforestation in occur could exceptions although, precipitation on depends largely rainfall where basins the as such, patterns circulation driven internally watersheds mountain Forested dependable to key a are (Switzerland (supplies freshwater HOFER. T/0339-FO/DEPARTMENT FORESTRY FAO
STATE OF THE WORLDS FORESTS 2003 Amazon basin. Even then, it has been estimated documented, although research is under way that complete deforestation and replacement in Central America(Calder, 1999b, as with non-forest vegetation would reduce basin reported by Kaimowitz, 2000 rainfall by less than 20 percent( Brooks et al 1997) Non-cloud forests and freshwater yield There are circumstances, however, in which Outside fog or tropical montane cloud forest forests intercept fog or low clouds(cloud regions, forests generally consume large forests), adding moisture to the site that would quantities of water. More than 100 watershed otherwise remain in the atmosphere. The experiments around the world have shown tha relationship between forests and the yield of forest removal increases stream flow, which freshwater differs between cloud forest and varies in magnitude with climate and forest type non-cloud forest conditions and diminishes as forests regenerate(e.g. Bariet aL., 1996: Bosch and Hewlett, 1982; Lesch and Cloud forests and freshwater yield Scott, 1997; Verry, Hornbeck and Todd, 2000; Cloud forests occur along coastal areas in Whitehead and Robinson, 1993). When other results show th common. Forests intercept atmospher following moisture (horizontal precipitation), which Removal of forest cover increases annual condenses on and drips from foliage, adding water yield by 60 to 650 mm. The size of the moisture to the soil. Rainfall is not increased increase is generally proportional to the but forests add moisture that low-growing amount of biomass removed and is greater in regetation would not. The following are wetter areas. Little effect has been reported in examples of freshwater augmentation by cloud dryland areas where annual precipitation is forests less than 400 mm Coastal forests in the fog belt of western Flow during dry seasons generally increases Oregon, the United States, augment water after forests are thinned or removed yield(Harr, 1982; Ingwersen, 1985). The Forests with high interception rates(e.g removal of old-growth conifer forests from conifers)or high transpiration rates(e. g the municipal watershed of Portland, eucalypts) yield less water than those with Oregon, reduced summer stream flow, but lower interception and transpiration rates the regrowth of vegetation caused stream Water yield would therefore be expected to flow levels to return to normal within five to increase when conifer forests are replaced by SIx years broadleaf forests and to decrease when Water augmentation by tropical montane broadleaf forests, shrubs or grasses are cloud forests varies with altitude, location replaced by conifers(see Box opposite) nd season( Bruijnzeel and Proctor, 1993) The ratio of horizontal precip FORESTS, FLOODS AND DEBRIS annual rainfall was shown to vary between FLOWS 4 and 85 percent, with higher values Forests produce low levels of storm flow and orresponding to dry seasons, while average greater soil stability than any other vegetation horizontal precipitation varied between 0.2 type because of their high infiltration rates, and 4 mm per day. Annual stream flow from protective ground cover, high consumption of tropical montane cloud forest for a given soil water and high tensile strength of roots rainfall was higher than from other tropical These attributes are particularly beneficial in forests. The stream flow response to mountainous terrain that is subject to torrential conversion of tropical montane cloud forest rainfall. Forest removal and road construction to other land uses has not been widely are problematic in such areas because they
2003 FORESTS S’WORLD THE OF STATE 76 estimated been has it, then Even. basin Amazon replacement and deforestation complete that basin reduce would vegetation forest-non with ,.al et Brooks (percent 20 than less by rainfall .(1997 which in, however, circumstances are There cloud (clouds low or fog intercept forests would that site the to moisture adding), forests The. atmosphere the in remain otherwise of yield the and forests between relationship and forest cloud between differs freshwater .conditions forest cloud-non yield freshwater and forests Cloud in areas coastal along occur forests Cloud montane tropical in also and climates temperate are conditions cloud low or fog where regions atmospheric intercept Forests. common which), precipitation horizontal (moisture adding, foliage from drips and on condenses ,increased not is Rainfall. soil the to moisture growing-low that moisture add forests but are following The. not would vegetation cloud by augmentation freshwater of examples .forests western of belt fog the in forests Coastal• water augment, States United the, Oregon The). 1985, Ingwersen; 1982, Harr (yield from forests conifer growth-old of removal ,Portland of watershed municipal the but, flow stream summer reduced, Oregon stream caused vegetation of regrowth the to five within normal to return to levels flow .years six montane tropical by augmentation Water• location, altitude with varies forests cloud .(1993, Proctor and Bruijnzeel (season and to precipitation horizontal of ratio The between vary to shown was rainfall annual values higher with, percent 85 and 4 average while, seasons dry to corresponding 2.0 between varied precipitation horizontal from flow stream Annual. day per mm 4 and given a for forest cloud montane tropical tropical other from than higher was rainfall to response flow stream The. forests forest cloud montane tropical of conversion widely been not has uses land other to way under is research although, documented as, 1999b, Calder (America Central in .(2000, Kaimowitz by reported yield freshwater and forests cloud-Non forest cloud montane tropical or fog Outside large consume generally forests, regions watershed 100 than More. water of quantities that shown have world the around experiments which, flow stream increases removal forest type forest and climate with magnitude in varies et Bari. g.e (regenerate forests as diminishes and and Lesch; 1982, Hewlett and Bosch; 1996., al ;2000, Todd and Hornbeck, Verry; 1997, Scott other When). 1993, Robinson and Whitehead are increases flow, forests replace uses land the show results, exceptions few With. sustained .following annual increases cover forest of Removal• the of size The. mm 650 to 60 by yield water the to proportional generally is increase in greater is and removed biomass of amount in reported been has effect Little. areas wetter is precipitation annual where areas dryland .mm 400 than less increases generally seasons dry during Flow• .removed or thinned are forests after .g.e (rates interception high with Forests• .g.e (rates transpiration high or) conifers with those than water less yield) eucalypts .rates transpiration and interception lower to expected be therefore would yield Water by replaced are forests conifer when increase when decrease to and forests broadleaf are grasses or shrubs, forests broadleaf .(opposite Box see (conifers by replaced DEBRIS AND FLOODS, FORESTS FLOWS and flow storm of levels low produce Forests vegetation other any than stability soil greater ,rates infiltration high their of because type of consumption high, cover ground protective .roots of strength tensile high and water soil in beneficial particularly are attributes These torrential to subject is that terrain mountainous construction road and removal Forest. rainfall they because areas such in problematic are
PART II SELECTED CURRENT ISSUES IN THE FOREST SECTOR A lesson from Fiji Afforestation reduced water yield to a water supply reservoir with lower interception and transpiration rates would have in Fiji(Drysdale, 1981) been preferred over conifers On the leeward side of two of the largest Fiji islands, he experience in Fiji convinced the Beijing Water Conser- 0000haof Pinus caribaea, plantedtodevelopawood-based vancy Bureauto reverse its plans to replace Chinese locust and dustry, replaced shrub vegetation. Six years after the forest shrubs with pine in the catchment area of the Miyun Reservoir, was planted, dry season flows to a downstream water supply a key municipal water source for Beijing. Planners had mistak- reservoir had decreased by 50 to 60 percent. The areas affor- enly thought that conversion to pine would increase water ested were not in a cloud-forest environment Had freshwater yield to the reservoir, whereas the result would have been the resources been considered in the afforestation plan, species oppo construction(below ) in mountain increase the frequency and magnitude of landslides and debris flows(Sidle, 2000) However, there is a limit to the protection that forest cover provides, as was found in Taiwan Province of China(see Box on next page), where early and managed for slope stabilization and torrent control (Lu, Cheng and Brooks, 2001). As th amount of rainfall becomes extreme. the extent to which forests can help to prevent landslides, A frequently asked question is the extent to which forest cover affects flooding. In northern Minnesota, the United States, rainfall-generated peak flows up to the 25-to 30-year recurrence interval (Ri)increased when 70 percent of the forest cover on a small watershed was clear-cut (Lu, 1994; Verry, 2000). Larger floods(RI >100 years)were not affected by forest cover removal, supporting Hewlett's(1982)claim that changes
77 SECTOR FOREST THE IN ISSUES CURRENT SELECTED II PART of magnitude and frequency the increase .(2000, Sidle (flows debris and landslides that protection the to limit a is there, However Taiwan in found was as, provides cover forest where), page next on Box see (China of Province forested are watersheds mountainous all nearly torrent and stabilization slope for managed and the As). 2001, Brooks and Cheng, Lu (control extent the, extreme becomes rainfall of amount ,landslides prevent to help can forests which to .diminishes flooding and flows debris to extent the is question asked frequently A northern In. flooding affects cover forest which generated-rainfall, States United the, Minnesota recurrence year-30 to- 25 the to up flows peak the of percent 70 when increased) RI (interval cut-clear was watershed small a on cover forest 100 > RI (floods Larger). 2000, Verry; 1994, Lu( ,removal cover forest by affected not were) years changes that claim) 1982 (s’Hewlett supporting reservoir supply water a to yield water reduced Afforestation .(1981, Drysdale (Fiji in ,islands Fiji largest the of two of side leeward the On based-wood a develop to planted, caribaea Pinus of ha 000 60 forest the after years Six. vegetation shrub replaced, industry supply water downstream a to flows season dry, planted was freshwater Had. environment forest-cloud a in not were estedaffor areas The. percent 60 to 50 by decreased had reservoir species, plan afforestation the in considered been resources have would rates transpiration and interception lower with .conifers over preferred been and locust Chinese replace to plans its reverse to Bureau vancyConser Water Beijing the convinced Fiji in experience The ,Reservoir Miyun the of area catchment the in pine with shrubs water increase would pine to conversion that thought enlymistak had Planners. Beijing for source water municipal key a the been have would result the whereas, reservoir the to yield .opposite road and) above (removal Tree mountain in) below (construction erosion soil serious cause can areas (Nepal (landslides and HOFER. T/0285-FO/DEPARTMENT FORESTRY FAO HOFER. T/0286-FO/DEPARTMENT FORESTRY FAO Fiji from lesson A
STATE OF THE WORLDS FORESTS 2003 incentives for people to avoid them. Terrain analysis based on Geographic Information Typhoons,landslides and debris flows Systems(GIS)offers the means to mark in Taiwan Province of hina hazardous terrain in mountainous watersheds (Gupta and Joshi, 1990; Sidle, 2000), and methods to delineate floodplains and define Floods, landslides and debris flows, resulting from an zones according to the type and degree of risk three to four typhoons a year, cause extensive loss of life and prop- are well known(Bedient and Huber, 1988).An erty on the mountainous island of Taiwan Province of China. About example of an incentive to change people's 53 percent of the island has slopes steeper than 21, and more than behaviour is the federal flood Insurance 100 peaks exceed 3 000 m above sea level(Lee, 1981). With shal- Program in the United States, under which low soils overlying weak, fractured and weathered geological for- insurance rates in areas adjacent to rivers are mations, landslides load steep channels, which become primed for linked to the degree of hazard During the particularly destructive Typhoon Herb in 1996, rain- FORESTS AND SEDIMENTATION fall athigherelevationsexceeded 1 985 mmin 42hours(Lu, Cheng Because watersheds with healthy forests and Brooks, 2001). Landslides and debris flows occurred through- the lowest levels of sediment of any cover type out the island, many along roads and in drainage channels where Brooks et al., 1997), it is not surprising that native forest had been converted to grow tea, vegetable crops and forests are often looked to as a means of but many in forested areas as well. Given the reducing levels of downstream sediment in amount and intensity of rainfall, debris flows and flooding oc- water supply reservoirs curred regardless of land use. Larson and Albertin(1984 )recommended reforestation to reverse a threefold increase in sedimentation in the Alhajuela Reservoir in Panama following the clearing of 18.2 percent of the watershed. Few such studies forest cover have little effect on large floods in people therefore suggest that the benefits from streams. Importantly, the 1.5-to 2-year rI forest cover in reservoir protection have been peak flows more than doubled when forest cover overestimated(Kaimowitz, 2000). Reasons for such scepticism include Extreme hydrological events are the result of inadequate monitoring, and therefore limited natural processes of erosion and sediment empirical evidence linking forest changes to motion interacting with human systems(Davies, reservoir sedimentation levels 1997). Where land scarcity concentrates people the fact that forest cover changes have and their dwellings in hazardous areas, disasters occurred over such small areas of watersheds will occur whether uplands are fully forested or that little effect has been observed not. This is the situation in Taiwan Province of the distance between upstream watershed China, with a population density approaching projects and downstream reservoirs, which 600 inhabitants per square kilometre. People masks the effects living on steep slopes, in the mouths of small the recognition that other factors, such as drainage basins and in floodplains are bound to non-forest land use can increase stream flow be vulnerable. a coordinated watershed peaks and affect sedimentation management programme among government Downstream sediment delivery is affected agencies has been suggested in order to address both by changes in stream flow discharge from this threat for both upstream and downstream upland watersheds and by alterations in riparian communities(Lu, Cheng and Brooks, 2001). areas along stream banks(Rosgen, 1994 Hazardous areas must be identified, and Tabacchi et aL., 2000). Sediment levels of rivers policies and institutions established to provide are determined by both sediment availability
2003 FORESTS S’WORLD THE OF STATE 78 in floods large on effect little have cover forest in RI year-2 to- 5.1 the, Importantly. streams major cover forest when doubled than more flows peak .removed was of result the are events hydrological Extreme sediment and erosion of processes natural ,Davies (systems human with interacting motion people concentrates scarcity land Where). 1997 disasters, areas hazardous in dwellings their and or forested fully are uplands whether occur will of Province Taiwan in situation the is This. not approaching density population a with, China People. kilometre square per inhabitants 600 small of mouths the in, slopes steep on living to bound are floodplains in and basins drainage watershed coordinated A. vulnerable be government among programme management address to order in suggested been has agencies downstream and upstream both for threat this .(2001, Brooks and Cheng, Lu (communities and, identified be must areas Hazardous provide to established institutions and policies Terrain. them avoid to people for incentives Information Geographic on based analysis mark to means the offers) GIS (Systems watersheds mountainous in terrain hazardous and), 2000, Sidle; 1990, Joshi and Gupta( define and floodplains delineate to methods risk of degree and type the to according zones An). 1988, Huber and Bedient (known well are s’people change to incentive an of example Insurance Flood Federal the is behaviour which under, States United the in Program are rivers to adjacent areas in rates insurance .hazard of degree the to linked SEDIMENTATION AND FORESTS export forests healthy with watersheds Because type cover any of sediment of levels lowest the that surprising not is it), 1997., al et Brooks( of means a as to looked often are forests in sediment downstream of levels reducing .reservoirs supply water recommended) 1984 (Albertin and Larson in increase threefold a reverse to reforestation in Reservoir Alhajuela the in sedimentation of percent 2.18 of clearing the following Panama some and, exist studies such Few. watershed the from benefits the that suggest therefore people been have protection reservoir in cover forest for Reasons). 2000, Kaimowitz (overestimated :include scepticism such limited therefore and, monitoring inadequate• to changes forest linking evidence empirical ;levels sedimentation reservoir have changes cover forest that fact the• watersheds of areas small such over occurred ;observed been has effect little that watershed upstream between distance the• which, reservoirs downstream and projects ;effects the masks as such, factors other that recognition the• flow stream increase can, use land forest-non .sedimentation affect and peaks affected is delivery sediment Downstream from discharge flow stream in changes by both riparian in alterations by and watersheds upland ;1994, Rosgen (banks stream along areas rivers of levels Sediment). 2000., al et Tabacchi availability sediment both by determined are of average an from resulting, flows debris and landslides, Floods About. China of Province Taiwan of island mountainous the on ertyprop and life of loss extensive cause, year a typhoons four to three than more and°, 21 than steeper slopes has island the of percent 53 for primed become which, channels steep load landslides, mationsfor geological weathered and fractured, weak overlying soils lowshal With). 1981, Lee (level sea above m 000 3 exceed peaks 100 .flows debris Cheng, Lu (hours 42 in mm 985 1 exceeded elevations higher at fallrain, 1996 in Herb Typhoon destructive particularly the During where channels drainage in and roads along many, island the outthrough occurred flows debris and Landslides). 2001, Brooks and and crops vegetable, tea grow to converted been had forest native the Given. well as areas forested in many but, palm nut betel .use land of regardless curredoc flooding and flows debris, rainfall of intensity and amount flows debris and landslides, Typhoons China of Province Taiwan in
PART II SELECTED CURRENT ISSUES IN THE FOREST SECTOR and stream flow discharge. The most effective parian forests discharge for transporting sediment over time is Forest buffers and agroforestry systems along that associated with the bank-full stage(when water bodies further improve water quality the river channel is full but not overflowing), Long neglected and often exploited, riparian correspo nding approximately to the forests help to stabilize stream banks, reduce average annual peak flow. When land use wastewater and chemical discharge into water increases the size of these flows the stream bodies from upland areas and maintain cooler channel becomes unstable and sediment levels water temperatures, thus improving dissolved increase, regardless of whether erosion rates oxygen levels in water( Brooks et al., 1997). The have been reduced Healthy riparian forests can water quality can be enhanced for human also reduce sediment levels by filtering out soil consumption, leading to better health and erosion inputs to channels and by maintaining productivity and greater diversity of aquatic stable stream banks. Degradation of both upland ecosystems, including mangrove forests. As a and riparian forests can therefore combine to result, healthy riparian forests increase fish increase sediment delivery to reservoirs Riparian systems are heavily utilized because FORESTS AND WATER QUALITY of their proximity to water and their high Water pollution impairs water use by productivity for grazing and farming, and it is downstream users and seriously affects human therefore unrealistic to protect them fro health. The exceptionally high quality of water uses. With proper management, however, discharged from forested watersheds is the main riparian forests and agroforestry systems along reason that protected forests are preferred for water bodies can mitigate the effects of nutrient, municipal watersheds. Forests efficiently cycle chemical and human waste discharge. At the nutrients and chemicals and decrease the same time, these systems can provide wood sediment exported, thus reducing pollutants forage and other products for the rural poor uch as phosphorus and some heavy metals. The lower rate of rainfall runoff also reduces the load WATERSHEDS: RECOGNIZING of all nutrients and pollutants entering water UPSTREAM-DOWNSTREAM LINKAGES bodies Scale and cumulative effects In many developing countries, the food and Freshwater benefits to downstream areas esource needs of the rural poor, coupled with naturally accompany sound management of land scarcity and institutional limitations, upland and riparian forests, but management constrain efforts to protect forested watersheds can also be directed to specific freshwater for municipal water supplies. However, th objectives. In either case, benefits may be problems of polluted drinking-water and masked by spatial aspects, for example the associated diseases significantly jeopardize the location and diffuse nature of land-use practices welfare of rural populations and urban and their effects: the scale of activities in communities alike. Water storage and transport proportion to watershed size; and the time facilities are sorely needed in many areas, along needed for benefits to be realized. Changes on with improved sanitation and water treatment. the land can have incremental effects that may Well-managed forested catchments above not be individually apparent but can be reservoirs can result in minimal requirements for considerable over the whole watershed and over water treatment. Echavarria and Lochman(1999) time. This complexity has clouded the view of reported that USSI billion spent on improved decision-makers in many parts of the world and management of the New York City watersheds weakened their commitment to watershed over ten years could save an outlay of US$4 management. However, these cumulative effects billion to $6 billion for construction of new water must be recognized in environmental and treatment facilities economic assessments
79 SECTOR FOREST THE IN ISSUES CURRENT SELECTED II PART effective most The. discharge flow stream and is time over sediment transporting for discharge when (stage full-bank the with associated that ,(overflowing not but full is channel river the the to approximately corresponding usually use land When. flow peak annual average stream the, flows these of size the increases levels sediment and unstable becomes channel rates erosion whether of regardless, increase can forests riparian Healthy. reduced been have soil out filtering by levels sediment reduce also maintaining by and channels to inputs erosion upland both of Degradation. banks stream stable to combine therefore can forests riparian and .reservoirs to delivery sediment increase QUALITY WATER AND FORESTS by use water impairs pollution Water human affects seriously and users downstream water of quality high exceptionally The. health main the is watersheds forested from discharged for preferred are forests protected that reason cycle efficiently Forests. watersheds municipal the decrease and chemicals and nutrients pollutants reducing thus, exported sediment The. metals heavy some and phosphorus as such load the reduces also runoff rainfall of rate lower water entering pollutants and nutrients all of .bodies and food the, countries developing many In with coupled, poor rural the of needs resource ,limitations institutional and scarcity land watersheds forested protect to efforts constrain the, However. supplies water municipal for and water-drinking polluted of problems the jeopardize significantly diseases associated urban and populations rural of welfare transport and storage Water. alike communities along, areas many in needed sorely are facilities .treatment water and sanitation improved with above catchments forested managed-Well for requirements minimal in result can reservoirs (1999 (Lochman and Echavarria. treatment water improved on spent billion 1$US that reported watersheds City York New the of management 4$US of outlay an save could years ten over water new of construction for billion 6 $to billion .facilities treatment forests Riparian along systems agroforestry and buffers Forest .quality water improve further bodies water riparian, exploited often and neglected Long reduce, banks stream stabilize to help forests water into discharge chemical and wastewater cooler maintain and areas upland from bodies dissolved improving thus, temperatures water The). 1997., al et Brooks (water in levels oxygen human for enhanced be can quality water and health better to leading, consumption aquatic of diversity greater and productivity a As. forests mangrove including, ecosystems fish increase forests riparian healthy, result .production because utilized heavily are systems Riparian high their and water to proximity their of is it and, farming and grazing for productivity all from them protect to unrealistic therefore ,however, management proper With. uses along systems agroforestry and forests riparian ,nutrient of effects the mitigate can bodies water the At. discharge waste human and chemical ,wood provide can systems these, time same .poor rural the for products other and forage RECOGNIZING: WATERSHEDS LINKAGES DOWNSTREAM–UPSTREAM effects cumulative and Scale areas downstream to benefits Freshwater of management sound accompany naturally management but, forests riparian and upland freshwater specific to directed be also can be may benefits, case either In. objectives the example for, aspects spatial by masked practices use-land of nature diffuse and location in activities of scale the; effects their and time the and; size watershed to proportion on Changes. realized be to benefits for needed may that effects incremental have can land the be can but apparent individually be not over and watershed whole the over considerable of view the clouded has complexity This. time and world the of parts many in makers-decision watershed to commitment their weakened effects cumulative these, However. management and environmental in recognized be must .assessments economic
STATE OF THE WORLDS FORESTS 2003 Cumulative effects of land use on downstream those that are not traded in the marketplace: and water flow, sediment loads and pollutants can water subsidies. In many parts of the world, best be observed on islands over a fey water is heavily subsidized and often considered kilometres rather than hundreds. For example, a free good. Its scarcity is now causing people to deforestation and cropping practices on islands determine the value of freshwater more in the Caribbean and the pacific have been realistically. In contrast, the economic benefits of linked to the degradation of estuaries, coral reefs well-managed or protected forests have not been and their dependent fisheries. In eastern fully considered in terms of avoided losses from Jamaica, the replacement of forests with upland soil erosion, debris flows, sedimentation and coffee farming has increased soil erosion and the floods, for example export of chemicals, which have contributed to Improved watershed economics may thus be the degradation of coral reefs(K Eckman, forthcoming as a result of water scarcity. What personal communication, 2002). Such linkages some are calling a new global water economy is are clear in river basins, but in larger systems the emerging, in which freshwater is viewed more impact may take decades or longer to become as an economic commodity than as a publicly evident, and may be masked by other land-use managed resource(Anderson, 2002). For practices. An example of such an impact is the example, in southern California, the United depletion of oxygen in the Gulf of Mexico, which States, farmers pay US$8. 11 per 1 000 of water has been traced in part to agricultural non-point in comparison with USSI 622 paid by the city of pollution of the Mississippi River basin in the Santa Barbara. Water there is more valuable tha United States Midwestern states in the United the crops being irrigated with the result that States are focusing on restoring riparian forests some farmers sell their supplies to and wetlands and improving agricultural land municipalities. In such instances, there may be use to reduce total maximum daily loads to the sound economic justification for managing Mississippi River, in accordance with federal forested watersheds for water supplies legislation calling on all states to improve The new water economy faces hurdles in paired bodies of water. Urban and peri-urban developing countries, where water has often orest and tree programmes are being developed been treated as a free good because of and promoted to address poverty and food longstanding practices and religious beliefs nsecurity as well as to support protection and (Rosegrant and Cline, 2002). More efficient water sustainable use of land resources allocation and innovative pricing policies can provide incentives to support forest Economic consideration management for water supply purposes. Policies Forest management and other watershed that continue to treat water as a free good or that improvements to protect and manage freshwater heavily subsidize it will continue to promote require economic justification. A watershed waste in developing and developed countries erspective provides clarity in determining the alike. Johnson, White and Perrot- Maitre(2001) ohnson, White and Perrot-Maitre(2001) have enhance the restoration, maintenance any can conomic value of forests for these purposes. have suggested financial mechanisms that emphasized the economic importance of the improvement of water-related services from water-related ecosystem services provided by forested watersheds forests. However, no comprehensive economic In most cases, the methodology to perform the analyses that consider the full range of these needed financial and economic analysis exists. benefits have so far been made, because of a Upstream and downstream data, sometimes number of difficulties. These include inadequate sorely lacking, are transformed into benefits and monitoring and evaluation of watershed services costs that can be contrasted under"with"and from forestry projects; difficulties in placing an "without"conditions(FAO, 1987). This approach accurate value on many services, particularly has been used to assess watershed projects in
2003 FORESTS S’WORLD THE OF STATE 80 downstream on use land of effects Cumulative can pollutants and loads sediment, flow water few a over, islands on observed be best ,example For. hundreds than rather kilometres islands on practices cropping and deforestation been have Pacific the and Caribbean the in reefs coral, estuaries of degradation the to linked eastern In. fisheries dependent their and upland with forests of replacement the, Jamaica the and erosion soil increased has farming coffee to contributed have which, chemicals of export ,Eckman. K (reefs coral of degradation the linkages Such). 2002, communication personal the systems larger in but, basins river in clear are become to longer or decades take may impact use-land other by masked be may and, evident the is impact an such of example An. practices which, Mexico of Gulf the in oxygen of depletion point-non agricultural to part in traced been has the in basin River Mississippi the of pollution United the in states Midwestern. States United forests riparian restoring on focusing are States land agricultural improving and wetlands and the to loads daily maximum total reduce to use federal with accordance in, River Mississippi improve to states all on calling legislation urban-peri and Urban. water of bodies impaired developed being are programmes tree and forest food and poverty address to promoted and and protection support to as well as insecurity .resources land of use sustainable considerations Economic watershed other and management Forest freshwater manage and protect to improvements watershed A. justification economic require the determining in clarity provides perspective .purposes these for forests of value economic have) 2001 (Maître-Perrot and White, Johnson the of importance economic the emphasized by provided services ecosystem related-water economic comprehensive no, However. forests these of range full the consider that analyses a of because, made been far so have benefits inadequate include These. difficulties of number services watershed of evaluation and monitoring an placing in difficulties; projects forestry from particularly, services many on value accurate and; marketplace the in traded not are that those ,world the of parts many In. subsidies water considered often and subsidized heavily is water to people causing now is scarcity Its. good free a more freshwater of value the determine of benefits economic the, contrast In. realistically been not have forests protected or managed-well from losses avoided of terms in considered fully and sedimentation, flows debris, erosion soil .example for, floods be thus may economics watershed Improved What. scarcity water of result a as forthcoming is economy water global new a calling are some more viewed is freshwater which in, emerging publicly a as than commodity economic an as For). 2002, Anderson (resource managed United the, California southern in, example m3 000 1 per 11.8$US pay farmers, States water of of city the by paid 622 1$US with comparison in than valuable more is there Water. Barbara Santa that result the with, irrigated being crops the to supplies their sell farmers some be may there, instances such In. municipalities managing for justification economic sound .supplies water for watersheds forested in hurdles faces economy water new The often has water where, countries developing of because good free a as treated been beliefs religious and practices longstanding water efficient More). 2002, Cline and Rosegrant( can policies pricing innovative and allocation forest support to incentives provide Policies. purposes supply water for management that or good free a as water treat to continue that promote to continue will it subsidize heavily countries developed and developing in waste (2001 (Maître-Perrot and White, Johnson. alike can that mechanisms financial suggested have and maintenance, restoration the enhance from services related-water of improvement .watersheds forested the perform to methodology the, cases most In .exists analysis economic and financial needed sometimes, data downstream and Upstream and benefits into transformed are, lacking sorely and” with “under contrasted be can that costs approach This). 1987, FAO (conditions” without“ in projects watershed assess to used been has
PART II SELECTED CURRENT ISSUES IN THE FOREST SECTOR Morocco and China, encompassing, but not (Eckman, Gregersen and Lundgren, 2000).A limited to, changes in forest cover and policy environment must be created that management( Brooks et al., 1981; Shuhuai et al., supports, rather than hinders, the integration of 2001 ). In both cases, watershed improvements, land and water management. including forests and agroforestry, were found Since watershed and political boundaries be economically viable(with economic rates rarely coincide, the coordination of land and of return of 10 to 16 percent)when production water management depends on organizations to and water resource benefits were combined resolve transboundary issues and water-use Hydrological computer models can be used to disputes. In the United States during the 1990 examine human-induced effects on watersheds. the absence of effective watershed- or basin Changes in water yield, flooding and sediment level organizations led to the formation of more transport, for example, can be simulated and than 1 500 watershed districts to deal with related to specific sites where economic benefits upstream-downstream issues(Lant, 1999). Nile- and costs are of interest. The cumulative effects basin countries established a partnership of nine of agricultural development, the loss of riparian riparian countries to resolve transboundary forests in floodplains and wetland drainage issues and to move towards more sustainable were simulated for a watershed of the development( Baecher et al, 2000). The Minnesota river basin in the united states inequities of water distribution in this region are using the Hydrocomp Simulation Program amplified because more than 80 percent of the Fortran(HSPF)model (Miller, 1999). These flow to the lower Nile, on which the Sudan and land-use changes increased annual stream flow Egypt depend, originates in mountainous and peak flow discharges, which can be related Ethiopia. Without cooperation and to"lost storage"in the basin. Hey (2001) coordination, disputes over water use and determined that the downstream damage opment could cle associated with a major recent flood could have A better understanding of the processes and been significantly reduced by restoring approaches required in large river basins is sufficient areas of riparian forest cover, needed and the International Year of floodplains and wetlands in the basin. He Freshwater in 2003 is an opportunity for concluded that farmers could justifiably be stakeholders to share experiences in order to compensated for such land conversion on the identify possible paths for the future basis of reduced economic losses from future flooding. Such innovative approaches need to CONCLUSIONS AND be expanded and considered for tropical RECOMMENDATIONS watersheds and developing countries, with The scarcity of freshwater is a global problem emphasis on developing computer simulation calling for more effective and efficient water models nagement, from local watersheds to major river basins. The International Year of Institutional and policy considerations Freshwater in 2003 can help to focus global Better management of forests and water attention on issues and solutions and on the resources to improve human welfare requires need for a comprehensive approach to cope more than just technical knowledge. While with scarcity, on the one hand, and excess,on technical information provides a foundation for the other Forests can have an important role in assessing upstream-downstream linkages and supplying freshwater, but their management carrying out economic analyses, transforming must complement water management. such information into management practices Technology exists for the most part, but equires the effective participation of cementation requires policies an stakeholders in order to develop a consensus nstitutions to promote intersectoral dialogue and provide incentives for implementation and cooperation. The following are some
81 SECTOR FOREST THE IN ISSUES CURRENT SELECTED II PART not but, encompassing, China and Morocco and cover forest in changes, to limited ,.al et Shuhuai; 1981., al et Brooks (management ,improvements watershed, cases both In). 2001 found were, agroforestry and forests including rates economic with (viable economically be to production when) percent 16 to 10 of return of .combined were benefits resource water and to used be can models computer Hydrological .watersheds on effects induced-human examine sediment and flooding, yield water in Changes and simulated be can, example for, transport benefits economic where sites specific to related effects cumulative The. interest of are costs and riparian of loss the, development agricultural of drainage wetland and floodplains in forests the of watershed a for simulated were ,States United the in basin River Minnesota – Program Simulation Hydrocomp the using These). 1999, Miller (model) HSPF (Fortran flow stream annual increased changes use-land related be can which, discharges flow peak and (2001 (Hey. basin the in” storage lost “to damage downstream the that determined have could flood recent major a with associated restoring by reduced significantly been ,cover forest riparian of areas sufficient He. basin the in wetlands and floodplains be justifiably could farmers that concluded the on conversion land such for compensated future from losses economic reduced of basis to need approaches innovative Such. flooding tropical for considered and expanded be with, countries developing and watersheds simulation computer developing on emphasis .models considerations policy and Institutional water and forests of management Better requires welfare human improve to resources While. knowledge technical just than more for foundation a provides information technical and linkages downstream–upstream assessing transforming, analyses economic out carrying practices management into information such of participation effective the requires consensus a develop to order in stakeholders implementation for incentives provide and A). 2000, Lundgren and Gregersen, Eckman( that created be must environment policy of integration the, hinders than rather, supports .management water and land boundaries political and watershed Since and land of coordination the, coincide rarely to organizations on depends management water use-water and issues transboundary resolve 1990s the during States United the In. disputes more of formation the to led organizations levelbasin or- watershed effective of absence the with deal to districts watershed 500 1 than nine of partnership a established countries basinNile). 1999, Lant (issues downstream–upstream transboundary resolve to countries riparian sustainable more towards move to and issues The). 2000., al et Baecher (development are region this in distribution water of inequities the of percent 80 than more because amplified and Sudan the which on, Nile lower the to flow mountainous in originates, depend Egypt and cooperation Without. Ethiopia and use water over disputes, coordination .arise clearly could development and processes the of understanding better A is basins river large in required approaches of Year International the and, needed for opportunity an is 2003 in Freshwater to order in experiences share to stakeholders .future the for paths possible identify AND CONCLUSIONS RECOMMENDATIONS problem global a is freshwater of scarcity The water efficient and effective more for calling major to watersheds local from, management of Year International The. basins river global focus to help can 2003 in Freshwater the on and solutions and issues on attention cope to approach comprehensive a for need on, excess and, hand one the on, scarcity with in role important an have can Forests. other the management their but, freshwater supplying .management water complement must but, part most the for exists Technology and policies requires implementation dialogue intersectoral promote to institutions some are following The. cooperation and
STATE OF THE WORLD'S FORESTs 2003 potential ways in which the management of Agroforestry systems need to be developed forests and water can be mutually supportive for upland watersheds in order to capture First, mountainous forested watershed the hydrological benefits of forests, while require special attention as the highest enhancing food and natural resource freshwater-yielding areas in the world, but also production for the rural poor as the source areas for landslides, torrents and Third, the potential exists to mitigate the floods. People inhabiting the headwater regions economic damage caused by floods and and those living in the downstream lowlands sediment delivery through forest management depend on freshwater from the uplands, and in uplands, riparian areas and floodplains also feel the effects of hydrometeorological Although the largest and most damaging flood extremes. Action to prevent or mitigate disasters in major rivers are not affected by the extent of in mountainous terrain should include forest cover, moderate and localized flood maintenance of healthy forest cover on increase when forests are removed forest mountainous watersheds that are subject to degradation brings with it many undesirable torrential rainfall effects on water flow and quality. Healthy development of programmes that combine upland and riparian forests can maintain low forest protection with zoning, floodplain levels of sediment delivery to rivers, lakes and management and engineering structures to reservoirs protect people from landslides, debris flows Fourth, a watershed perspective should be and floods incorporated into the planning and Second, forests can be managed to enhance management of forests, water, and urban and freshwater supplies, but as a component of agricultural land use. This perspective is needed comprehensive and multifaceted water at the local level as well as the highest management programmes. The economic value government levels in order to promote of water and its source areas must be recognized. sustainable solutions By reducing water subsidies and treating water Fifth, incentives and the means to achieve as a commodity rather than a free good, freshwater objectives must be provided through economic incentives can support better forest and other land-use management policies management in the following ways and institutions. from the local watershed level The water yield of municipal watersheds in to the river basin level. Intersectoral dialogue non-cloud forest conditions can be and cooperation are necessary to achieve augmented when tree species with low management objectives and to resolve inequities consumptive use replace those with high in terms of who pays for and who benefits from consumptive use or when forest stands are changes in upstream and downstream resource periodically thinned and harvested use. Expanded economic analysis is needed to In cloud-forest conditions, mature and old- understand these inequities better and to resolve growth forests should be protected and them. The emerging water economy will managed to sustain stream flow during facilitate the justification of land-use changes to dry periods enhance water supplies. Consideration should parian forests should be managed to be given to compensating inhabitants who protect water quality, which can in turn mprove forests and other land uses that reduce enhance the productive capacity of aquatic downstream losses. The policy environment and ecosystems and improve the health and institutional support may be enhanced througl welfare of local human populations. In improved understanding of the processes ddition, full use should be made of and required approaches for upstream- agroforestry buffer systems that can achieve downstream management systems these goals and also provide food, fodder context of better water resource and wood products management and sustainable development
2003 FORESTS S’WORLD THE OF STATE 82 of management the which in ways potential .supportive mutually be can water and forests watersheds forested mountainous, First highest the as attention special require also but, world the in areas yielding-freshwater and torrents, landslides for areas source the as regions headwater the inhabiting People. floods lowlands downstream the in living those and and, uplands the from freshwater on depend hydrometeorological of effects the feel also disasters mitigate or prevent to Action. extremes :include should terrain mountainous in on cover forest healthy of maintenance• to subject are that watersheds mountainous ;rainfall torrential combine that programmes of development• floodplain, zoning with protection forest to structures engineering and management flows debris, landslides from people protect .floods and enhance to managed be can forests, Second of component a as but, supplies freshwater water multifaceted and comprehensive value economic The. programmes management .recognized be must areas source its and water of water treating and subsidies water reducing By ,good free a than rather commodity a as better support can incentives economic .ways following the in management in watersheds municipal of yield water The• be can conditions forest cloud-non low with species tree when augmented high with those replace use consumptive are stands forest when or use consumptive .harvested and thinned periodically and protected be should forests growthold and mature, conditions forest-cloud In• during flow stream sustain to managed .periods dry to managed be should forests Riparian• turn in can which, quality water protect aquatic of capacity productive the enhance and health the improve and ecosystems In. populations human local of welfare of made be should use full, addition achieve can that systems buffer agroforestry fodder, food provide also and goals these .products wood and developed be to need systems Agroforestry• capture to order in watersheds upland for while, forests of benefits hydrological the resource natural and food enhancing .poor rural the for production the mitigate to exists potential the, Third and floods by caused damage economic management forest through delivery sediment .floodplains and areas riparian, uplands in floods damaging most and largest the Although of extent the by affected not are rivers major in can floods localized and moderate, cover forest Forest. removed are forests when increase undesirable many it with brings degradation Healthy. quality and flow water on effects low maintain can forests riparian and upland and lakes, rivers to delivery sediment of levels .reservoirs be should perspective watershed a, Fourth and planning the into incorporated and urban and, water, forests of management needed is perspective This. use land agricultural highest the as well as level local the at promote to order in levels government .solutions sustainable achieve to means the and incentives, Fifth through provided be must objectives freshwater policies management use-land other and forest level watershed local the from, institutions and dialogue Intersectoral. level basin river the to achieve to necessary are cooperation and inequities resolve to and objectives management from benefits who and for pays who of terms in resource downstream and upstream in changes to needed is analysis economic Expanded. use resolve to and better inequities these understand will economy water emerging The. them to changes use-land of justification the facilitate should Consideration. supplies water enhance who inhabitants compensating to given be reduce that uses land other and forests improve and environment policy The. losses downstream :through enhanced be may support institutional processes the of understanding improved• –upstream for approaches required and the in systems management downstream resource water better of context ;development sustainable and management
PART II SELECTED CURRENT ISSUES IN THE FOREST SECTOR expanded educational and training Brooks, K.N., Ffolliott, P. E, Gregersen, H M. & programmes that are directed to local De Bano, L.E. 1997. Hydrology watershed inhabitants up to the highest-level watersheds.2nd edition.Ames,lowa,USA,lowa better understanding and reconciliation of Brooks,KN, Gregersen, HM,Berglund, E.R.& the role of forests in freshwater management, Tayaa, M. 1981. Economic evaluation of watershed with emphasis on demonstration and projects: an overview of methodology and extension programmes aimed at local users application. Water Resources Bulletin, 18: 245-25 of land and water ruijnzeel, L.A. Proctor, J. 1993. Hydrology and expanded monitoring and evaluation of biogeochemistry of tropical montane cloud forests projects, as well as improved research on what do we really know? In L.S. Hamilton, JO tropical forested watersheds in developing Juvik e.n. Scatena, eds. Tropical montane cloud countries, given that many of the questions forests, Pp 38-78. New York, Springer-Verlag asked in the 1970s and 1980s about the Calder, L.R. 1999a. The blue revolution land use and hydrological role of tropical forests are sti integrated water resource management. London, largely unanswered, or at least not well Earthscan documented Calder. l.R. 1999b. Panama Canal watershed Socio-economic aspects as well as technical hydrological study preparation (Mimeo) components need to be stressed so that the avies, T.R.H. 1997 Using hydroscience and resulting information can provide the hydrotechnical engineering to reduce debris flow foundation for developing new technology and hazards. In C. Chen, ed Debris-flow hazards policies to enhance people' s welfare through mitigation: mechanics, Prediction, and assessment, Pp improved forest and freshwater management. 787-810. Proceedings of the 1st International Conference of the American Society of Civil Engineers. New York, American Society of Civil REFERENCES Drysdale, P.J. 1981. Status of general and forest hydrology research in Fiji. Working paper. In Anderson, T L. 2002. Water: from a public resource to Country papers on the status of watershed forest a market commodity. Water Resources Impact, 4(1) influence research in Southeast Asia and the Pacific Honolulu, Hawaii, USA, East-West Center. Baecher, G.B., Anderson, R, Britton, B, Brooks, K& Echavarria, M. &e Lochman, L. 1999. Policy mechanisms audet, 2000 The Nile Basin: environmental for watershed conservation: case studies. Arlington, transboundary opportunities and constraints analy Virginia, USA, Nature Conservancy kman, K, Gregersen, H M. Lundgren, A L 2000 Group, for the United States Agency for Watershed management and sustainable nternational Development (USAID) development: lessons learned and future directions Bari, M.A., Smith, N, Ruprecht, J K& Boyd, B w In Land stewardship in the 21st century: the 1996. Changes in stream flow components following contributions of watershed management, Pp 37-43 logging and regeneration in the southern forest of Proceedings, Rocky Mountain Research Station, western Australia. Hydrological Processes, 10: 447-461. RMRS-P-13. Fort Collins, Colorado, USA, United Bedient, P.B. Huber, W.C. 1988. Hydrology and flood States Department of Agriculture(USDA)Forest plain analysis. Reading, Massachusetts, USA Service Falkenmark, M. 1989. The massive water scarcity now Bosch, J M.& Hewlett, J D. 1982. A review of threatening Africa-why isn't it being addressed? catchment experiments to determine the effect of ambio,18(2)112-118 vegetation changes on water yield and FAO. 1987. Guidelines for economic appraisal of watershed evapotranspiration. ournal of Hydrology, 55: 3-23. management projects, by H.M. Gregersen, K N
83 SECTOR FOREST THE IN ISSUES CURRENT SELECTED II PART training and educational expanded• local to directed are that programmes level-highest the to up inhabitants watershed ;makers-policy of reconciliation and understanding better• ,management freshwater in forests of role the and demonstration on emphasis with users local at aimed programmes extension ;water and land of of evaluation and monitoring expanded• on research improved as well as, projects developing in watersheds forested tropical questions the of many that given, countries the about 1980s and 1970s the in asked still are forests tropical of role hydrological well not least at or, unanswered largely .documented technical as well as aspects economic-Socio the that so stressed be to need components the provide can information resulting and technology new developing for foundation through welfare s’people enhance to policies ◆ .management freshwater and forest improved REFERENCES to resource public a from: Water. 2002. L.T, Anderson :(1(4, Impact Resources Water. commodity market a .5–4 & .K, Brooks., B, Britton., R, Anderson., B.G, Baecher environmental: Basin Nile The. 2000. J, Gaudet .analysis constraints and opportunities transboundary Resources International, DC, Washington. Draft for Agency States United the for, Group .(USAID (Development International .W.B, Boyd. & K.J, Ruprecht., N, Smith., A.M, Bari following components flow stream in Changes. 1996 of forest southern the in regeneration and logging .461–447: 10, Processes Hydrological. Australia western flood and Hydrology. 1988. C.W, Huber. & B.P, Bedient ,USA, Massachusetts, Reading. analysis plain .Wesley-Addison of review A. 1982. D.J, Hewlett. & M.J, Bosch of effect the determine to experiments catchment and yield water on changes vegetation .23–3: 55, Hydrology of Journal. evapotranspiration & .M.H, Gregersen., F.P, Ffolliott., N.K, Brooks of management the and Hydrology. 1997. F.L, DeBano Iowa, USA, Iowa, Ames. edition 2nd. watersheds .Press University State & .R.E, Berglund., M.H, Gregersen., N.K, Brooks watershed of evaluation Economic. 1981. M, Tayaa and methodology of overview an: projects .250–245: 18, Bulletin Resources Water. application and Hydrology. 1993. J, Proctor. & A.L, Bruijnzeel :forests cloud montane tropical of biogeochemistry .O.J, Hamilton. S.L In? know really we do what cloud montane Tropical. eds, Scatena. N.F & Juvik .Verlag-Springer, York New. 78–38. pp, forests and use land, revolution blue The. 1999a. R.I, Calder ,London. management resource water integrated .Earthscan :watershed Canal Panama. 1999b. R. I, Calder (Mimeo. (preparation study hydrological and hydroscience Using. 1997. H.R.T, Davies flow debris reduce to engineering hydrotechnical hazards flow-Debris. ed, Chen. C In. hazards .pp, assessment and, prediction, mechanics: mitigation International 1st the of Proceedings. 810–787 Civil of Society American the of Conference Civil of Society American, York New. Engineers .Engineers forest and general of Status. 1981. J.P, Drysdale In. paper Working. Fiji in research hydrology forest watershed of status the on papers Country .Pacific the and Asia Southeast in research influence .Center West-East, USA, Hawaii, Honolulu mechanisms Policy. 1999. L, Lochman. & M, Echavarria ,Arlington. studies case: conservation watershed for .Conservancy Nature, USA, Virginia .2000. L.A, Lundgren. & M.H, Gregersen., K, Eckman sustainable and management Watershed .directions future and learned lessons: development the: century 21st the in stewardship Land In .43–37. pp, management watershed of contributions ,Station Research Mountain Rocky, Proceedings United, USA, Colorado, Collins Fort. 13-P-RMRS Forest) USDA (Agriculture of Department States .Service now scarcity water massive The. 1989. M, Falkenmark ?addressed being it t’isn why – Africa threatening .118–112): 2(18, Ambio watershed of appraisal economic for Guidelines. 1987. FAO .N.K, Gregersen. M.H by, projects management