Watershed Analysis for the Mesoamerican Reef Project Overview

Transcription

1 Watershed Analysis fr the Mesamerican Reef Prject Overview This dcument prvides a brief verview f a hydrlgic analysis implemented by the Wrld Resurces Institute (WRI) as part f the Internatinal Cral Reef Actin Netwrk (ICRAN) Mesamerican Reef (MAR) partnership. The bjective f the analysis was t quantify the impact f human alteratin f the landscape n land-based threats t the MAR t infrm land-use planning, agricultural plicy and practice, cnservatin pririty setting, and castal threat mitigatin effrts. Over a tw year perid, WRI cllabrated with many partners in the regin t evaluate sediment and nutrients cming frm land in ver 400 watersheds that discharge alng the MAR. The analysis evaluates the amunt f sediment and nutrients (nitrgen and phsphrus) cming frm each plt f land; the amunt f erded sediment and nutrients reaching the river muth (castal discharge pint); and the amunt f sediment reaching the reef. In additin, the analysis prvides estimates f the increase in sediment and nutrient delivery resulting frm human activities, and predictins f future sediment and nutrient delivery (in 2025) given varying land-use scenaris. This analysis is the first f this scpe and level f detail fr the MAR regin. The results prvide a preliminary verview f reginal patterns f sediment and nutrient runff and delivery, and indicate hw human alteratin f the landscape can influence these patterns. T ensure that the prject s results and analytical methds supprt actin in the regin, WRI makes the underlying data, analytical methd, and mdeling tls publicly available, and has cnducted training sessins with users in the regin. Based n this training, reginal users can implement mre detailed, fcused analyses fr smaller areas, calibrating them t lcal cnditins. All data used in the analysis and all mdel results, accmpanied by metadata, are prvided n the data CD, Watershed Analysis fr the Mesamerican Reef, WRI/ICRAN MAR prject, The data CD prvides a summary reprt in English and Spanish describing the analysis methd and results, as well as digital maps f key results.

2 Prject Backgrund Shared by Mexic, Belize, Guatemala, and Hnduras, the Mesamerican Reef (MAR), stretches ver 1,000 km, and is the largest cntinuus reef in the Western Hemisphere. Alteratin f the natural landscape fr develpment, rad cnstructin, r agriculture can have adverse impacts n cral reefs thrugh increased delivery f sediment, nutrients, and ther pllutants t castal waters. Threats frm land clearing are higher in areas f steep slpe, intense precipitatin, and mre erdible sils. Apprpriate land-use practices in ersin-prne areas are essential fr watershed management t minimize the transprt f sediment, nutrients, and ther pllutants t cral reefs. In the Mesamerican regin, ver 300,000 hectares f land is allcated t banana, il palm, sugar cane, citrus, and pineapple crp prductin. Erded sediments and fertilizer and pesticide residues used by farms drain thrugh rivers and streams and enter castal waters alng the Mesamerican reef. As part f the ICRAN MAR prject, the Wrld Resurces Institute (WRI) partnered with UNEP-Wrld Cnservatin Mnitring Centre (WCMC) and the Wrld Wildlife Fund (WWF) t prvide cmprehensive watershed analysis t cmplement the ICRAN MAR prject s activities n Sustainable Fisheries and Sustainable Turism. The ICRAN MAR watershed analysis was develped t prduce infrmatin and tls fr examining the ptential impact f different land use and develpment ptins in the regin and the assciated impacts n water quality n the MAR. The prject bjectives are t: Link patterns f land use within watersheds t the impacts at cral reefs, and identify reefs at greatest risk f degradatin; Identify watersheds mst vulnerable t ersin and thse which cntribute the mst sediment and pllutin t castal waters; Adapt tls t frecast ptential trends, evaluate different plicy r develpment ptins, and facilitate imprved land management within the regin; Use the results f the mdels and diagnstic tls t help educate and encurage key stakehlders t adpt a suite f better management practices t reduce impacts n the castal and marine resurces. Surce: Sylvia Marin, WWF Surce: Lauretta Burke, WRI The watershed prject includes analytical cmpnents lking at land cver change and assciated impacts n runff, ersin, and sediment and pllutant delivery t and transprt within castal waters. It als includes n-the-grund activities with agricultural businesses t implement better management practices. Many lcal partners were cnsulted n mdeling methds, fr data input and evaluatin, and n agricultural management practices. Three ICRAN partners cllabrated n this effrt: UNEP-WCMC develped land cver change scenaris and prvided data sets as input t the hydrlgic mdeling; WRI implemented the watershed delineatin and hydrlgic analysis fr the MAR regin, perfrmed analysis f vulnerability t ersin, and crdinated the circulatin mdeling alng the MAR; WWF led the wrk with agri-business (banana, pineapple, citrus and sugar) t implement better management practices, fcused n reducing the presence f pesticides in the MAR marine envirnment and cntrlling sil ersin frm majr cmmercial agricultural sectrs. 2

3 Overview f the Methdlgy In cllabratin with partners in the MAR regin, WRI: Implemented a watershed delineatin fr all land areas draining alng the Mesamerican reef; Implemented a hydrlgic analysis using the Nnpint-Surce Pllutin and Ersin Cmparisn Tl (N-SPECT) mdel t examine surces f sediment and nutrients frm this entire drainage area, as well as the delivery f sediment and nutrients t castal waters; Applied this hydrlgic analysis tl t examine sediment and nutrient delivery fr several land cver scenaris (current land cver, riginal r natural land cver, and three scenaris f land cver in 2025 scenari data prvided by UNEP-WCMC); Prvided utputs f the hydrlgic analysis as inputs t a circulatin mdel implemented by the University f Miami t examine sediment transprt alng the MAR; and Cllabrated with partners n calibratin and validatin f mdel results. Key Findings This hydrlgic analysis serves t integrate a wide range f data, and adapt mdeling tls fr an innvative, regin-wide analysis fr the MAR. The regin-wide results shuld be cnsidered preliminary and indicative f the verall pattern and magnitude f ersin and nutrient and sediment delivery acrss the regin. An imprtant aspect f the prject is t prvide these mdeling tls t partners in the MAR regin s that they might apply them at higher reslutin t prduce mre detailed results fr smaller areas within the MAR regin. This apprach will allw fr refinement and better calibratin f the mdel t lcal circumstances within the regin. The rigin f sediments and nutrients reaching the MAR: Of the 400 watersheds in the MAR regin, the Ulua watershed in Hnduras was fund t be the largest cntributr f sediment, nitrgen, and phsphrus. Other large rivers fund t be significant cntributrs f sediment and nutrients are the Patuca (in Hnduras), Mtagua (in Guatemala and Hnduras), Aguan (in Hnduras), Dulce (in Guatemala), Belize River (in Belize), and Tint Negr (in Hnduras). 3

4 The rigin f sediments and nutrients reaching the MAR: Mst f the sediment and nutrients delivered by watersheds alng the MAR riginate in Hnduras. It is estimated that ver 80% f sediment and ver half f all nutrients (bth nitrgen and phsphrus) riginate in Hnduras. Guatemala was identified as a surce f abut ne-sixth f all sediments and abut ne-quarter f all nitrgen and phsphrus entering castal waters alng the MAR. The mdeling suggests that cmpared t the ther cuntries, relatively minr percentages f the reginal sediment lad cme frm Belize and Mexic. Belize cntributes between 10-15% f nutrients and Mexic is estimated t cntribute abut 5%f the nutrients frm all mdeled watersheds. The estimate fr Mexic is prbably an underestimate, as the cntributin f undergrund rivers is nt included in this analysis. Runff, ersin, and nutrient delivery t castal waters are increasing: As a result f human alteratin f the landscape, runff and assciated river discharge at river muths has nearly dubled; sediment delivery at river muths has increased by a factr f 20; nitrgen delivery has increased by a factr f 3, and phsphrus delivery by a factr f 7. (Ratis are based n mdel results fr current (2003/04) land cver and n hypthetical natural (unaltered) land cver.) The ptential impacts f develpment and land-use paths are varied: Under land-use scenaris which favr free markets and little plicy regarding the envirnment, nutrient delivery is likely t increase by abut 10% by 2025, while sediment delivery might increase by 13% r mre. If envirnmental plicies that favr sustainable develpment are implemented, nutrient and sediment delivery are likely t be reduced by at least 5% frm current levels, fstering recvery f degraded crals. Implementatin f better agricultural management practices will yield additinal reductins in sediment and nutrient delivery beynd thse evaluated in this study, which has fcused n the effect f changes in land cver. 4

5 Cnclusin frm the Analysis Plicy actin is needed t address the cntributins frm agricultural lands. Mst f the sediment and nutrients delivered t the MAR frm watersheds in the regin cme frm agricultural lands in Hnduras and Guatemala. The cntributins f Belize and Mexic are substantially less, but still pse a threat alng their casts. Prmising initiatives t decrease pllutin within the regin are underway, including: sustainable frestry management and integrated watershed management in Guatemala; imprved land use planning, refrestatin and sil cnservatin prgrams in Hnduras; and similar initiatives in Belize and Mexic. These imprtant effrts need public supprt, recgnitin, and cntinued investment. Results can help identify areas in need f better agricultural management. This analysis identified vulnerable areas where cnversin t an ersive land use shuld be avided, r where cnverted cnservatin practices shuld be implemented. It als identified areas with high ersin and nutrient runff, where better agricultural management practices shuld be targeted. Plicies that supprt sustainable develpment can reduce sediment and nutrient delivery. As evidenced by ur findings, land-use planning, integrated watershed management, and ther plicies that supprt sustainable develpment can help t lessen ersin and pllutin runff, thereby decreasing sediment and nutrients reaching the MAR. Mre detailed mdeling is needed t create mre accurate infrmatin at higher reslutins. Reginal-scale analyses are useful fr prviding an verview and fr priritizing areas in which actin is needed. Hwever, lcal analyses prvide mre detailed and accurate infrmatin that plicymakers need in rder t target their interventins. The tls prvided n the data CD, Watershed Analysis fr the Mesamerican Reef (WRI/ICRAN MAR prject, 2006), allw users t perfrm mre detailed analyses f sediment and nutrient delivery within smaller areas in the MAR regin, such as at the watershed level. Mre specifically, the mdel can be applied t individual watersheds r grups f watersheds using data prvided r with the user s wn data. Mre detailed lcal mdeling will imprve the accuracy f the results, by using higher reslutin data n slpes and land cver, and by calibrating the mdel t lcal sils and precipitatin regimes. It wuld be valuable t extend the current analysis t include the effect f imprved agricultural management practices n ersin and pllutant runff. Such an extensin wuld require detailed infrmatin n hw each practice influences ersin rates and pllutant runff. Once such infrmatin is available, it shuld be pssible t use the mdel t evaluate reductins by treating each management interventin n each land cver type as a unique categry with specific ersin and pllutant runff 5

6 characteristics. Fr example, citrus grves with cver crps planted t reduce ersin might be treated as a separate categry. Analyses such as these can help t evaluate prgress in reducing land-based surces f threat. A number f natinal initiatives, as well as dnr-funded reginal initiatives, seek t reduce r mitigate threats t the MAR. This analysis can help these initiatives t estimate their prgress by giving them the infrmatin they need t ensure they are mving in the right directin. Transnatinal natural resurce management can be strngly supprted by analyses such as these. T mitigate and reduce the land-based threats t the MAR, cnstructive reginal cperatin amng a variety f stakehlders is necessary. Examples include the multilateral cperatin agreements amng the fur cuntries invlved in this analysis, and agreements between the agriculture and turism sectrs and civil sciety grups. This tl wrks acrss brders and sectrs, creating infrmatin that allws prductive discussin n threat rigins and ptential mitigatin measures. By spnsring technical trainings (see right) and ther activities, the Internatinal Cral Reef Actin Netwrk (ICRAN) cllabratin will cntinue t supprt the applicatin f analysis results and mdeling tls in the regin. Fr infrmatin n future ICRAN activities, visit The full paper and all high reslutin maps are available n the CD, which is available thrugh ICRAN MAR and WRI. Surce: ICRAN MAR Fr questins r cmments abut this analysis please cntact: Lauretta Burke, Senir Assciate lauretta@wri.rg Zachary Sugg, Research Assciate zsugg@wri.rg Wrld Resurces Institute 10 G St. NE, Washingtn, DC Tel: +1 (202) Fax: +1(202) reefsatrisk.wri.rg Liza Karina Agudel, Crdinatr lagudel@icran.rg ICRAN-Mesamerican Reef Alliance Fisheries Multicmplex Building Princess Margaret Drive Belize City, Belize Tel: Fax: