Ahmed Istak, Das Pan Nibedita, Debnath Jatan, Bhowmik Moujuri
Department of Geography and Disaster Management, Tripura University, Agartala, Tripura, India.
Environ Monit Assess. 2017 Oct 31;189(11):600. doi: 10.1007/s10661-017-6315-6.
Erosion-induced land degradation problem has emerged as a serious environmental issue across the world. Assessment of this problem through modelling can generate valuable quantitative information for the planners to identify priority areas for proper soil conservation measures. The Gumti River basin of Tripura falls under humid tropical climate and experiences soil erosion for a prolonged period which has turned into a major environmental issue. Increased sediment supply through top soil erosion is one of the major reasons for reduced navigability of this river. Thus, the present study is an attempt to prioritize the sub-watersheds of the Gumti basin by estimating soil loss through the USLE (Universal Soil Loss Equation) model. For that purpose, five parameters of the USLE model were processed, computed and overlaid in a GIS environment. The result shows that potential mean annual soil loss of the Gumti basin ranges between 0.03 and 114.08 t ha year. The resultant values of soil loss were classified into five categories considering the minimum and maximum values. It has been identified that low, moderate, high, very high and severe soil loss categories occupy 68.71, 8.94, 5.86, 5.02 and 11.47% of the basin respectively. Moreover, it has been recognised that sub-watersheds like SW7, SW8, SW12, SW21, SW24 and SW29 fall under very high priority class for which mitigation measures are essential. Therefore, the present study recommends mitigation measures through terrace cultivation, as an alternative of shifting cultivation in the hilly areas and through construction of check dams at the appropriate sites of the erosion prone sub-watersheds. Moreover, proper afforestation programmes that have been implemented successfully in other parts of Tripura through the Japan International Cooperation Agency, Joint Forest Management, and National Afforestation Programme should be initiated in the highly erosion-prone areas of the Gumti River basin.
侵蚀导致的土地退化问题已成为全球一个严重的环境问题。通过建模评估这一问题可为规划者提供有价值的定量信息，以便确定采取适当土壤保护措施的优先区域。特里普拉邦的古姆蒂河流域属于湿润热带气候，长期遭受土壤侵蚀，这已成为一个重大环境问题。表层土壤侵蚀导致沉积物供应量增加是该河通航能力下降的主要原因之一。因此，本研究试图通过通用土壤流失方程（USLE）模型估算土壤流失量，从而对古姆蒂河流域的子流域进行优先排序。为此，在地理信息系统（GIS）环境中对USLE模型的五个参数进行了处理、计算和叠加。结果表明，古姆蒂河流域潜在的年均土壤流失量在0.03至114.08吨/公顷·年之间。考虑到最小值和最大值，将土壤流失的计算结果分为五类。已确定低、中、高、极高和严重土壤流失类别分别占该流域的68.71%、8.94%、5.86%、5.02%和11.47%。此外，已认识到SW7、SW8、SW12、SW21、SW24和SW29等子流域属于极高优先级类别，必须采取缓解措施。因此，本研究建议通过梯田种植采取缓解措施，作为山区轮垦的替代方法，并在易发生侵蚀的子流域的适当地点修建拦沙坝。此外，应在古姆蒂河流域极易发生侵蚀的地区启动通过日本国际协力机构、联合森林管理和国家造林计划在特里普拉邦其他地区成功实施的适当造林计划。
