Developing GIS-based decision support system for soil and water conservation : a case study of the Upper Nam Haeng Watershed, Northern Thailand | |
| Author | Somnuck Pongsai |
| Call Number | AIT Diss. no.NR-10-05 |
| Subject(s) | Soil conservation--Geographic information systems--Thailand, Northern Water conservation--Geographic information systems--Thailand, Northern Upper Nam Haeng Watershed (Thailand) |
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Philosophy in Natural Resources Management, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. NR-10-05 |
| Abstract | Accelerated erosion in the steep slopes of northern Thailand has been a major problem for centuries. Unsustainable agricultural practices have degraded some of this land and are responsible for accelerating soil erosion. Eros ion problems on farm fields reduce crop production. The consequence of on-site erosion problems is sediment yield (SY) from the watershed, which results in reservoir sedime ntation, etc. This a ffects not only the downstream environment, but al so the socioeconomic developm ent of the region. In order to reduce soil erosion and prom ote sustainable agriculture, more information about soil erosion and sediment yield levels and the benefit returns under optimal soil and water conservation (SWC) practices are required, together with a suitable decision support system (DSS) for evaluation. A DSS is necessary for selecting the optimal SWC and for demonstrating the success of the project investment. The modified universal soil loss equation (M USLE) approach has been used to estimate SY at various sites. Some errors, however , have been associated with both USLE and runoff model estimates, resulting in under and over prediction. However, some errors associated with USLE – especially slope fact ors in terms of the limited existing data on steep slopes are still unclear in their applica tion to site-specific watersheds. The accuracy testing, calibrating and validating was conducted in Huai Khun Satan Catchment, Thailand. Experimental plots were esta blished at various inclinati ons (9, 16, 25, 30 and 35%), using the S factor from the classic USLE and the McCool model. SY was recorded from 27 rainfall events. The classic USLE had resulted in smaller relative error (RE) compared with McCool's at plots on slopes of 9% and 16%, while McCool's model preformed better at plots on slopes of over 16%. The calibration of the S factor then wa s made for two slope range intervals, and the equation was later adjust ed. The results revealed that an acceptable accuracy can be obtained through a model calib ration. This result reflects that MUSLE has some errors associated with USLE, especially in regard to slope factors when beyond the slope range of the ex trapolated model. The DSS in this research was developed for facilitating the best multi-objective selection of SWC practice for the various land unit t ypes (LUTs) in a watershed, based upon the effectiveness and cost-benefit return. The system has been developed by integrating the MUSLE, soil loss, nutrient loss, economic, and social decision element models, via the analytical hierarchy process optimization appr oach, into one system, using ArcView. The application was tested in the upper Nam H aeng watershed, Thailand. The proposed optimal SWC practices for 31 LUTs, which were base d upon the similarity of SWC requirements in terms of physical settings, included a vari ety of terrace practices and cropping systems, with a satisfactory economic re turn and acceptable levels of soil erosion. The findings show that this erosion control project of th is watershed is quite attractive in terms of economic feasibility of investment. It is suggest ed that this system can be applied to other watersheds for evaluating er osion and benefit return und er various land management regimes and consistency criteria. Developmen t of such a system could provide all the essential analytical tools to a ssist planners in soil and wate r conservation decision making at the watershed level. |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. NR-10-05 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Development and Sustainability (DDS) |
| Academic Program/FoS | Natural Resources Management (NRM) |
| Chairperson(s) | Schmidt-Vogt, Dietrich (Co-Chairperson) ;Shrestha, Rajendra P. (Co-Chairperson); |
| Examination Committee(s) | Clemente, Roberto S. ;Apisit Eiumnoh; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2010 |