Hydrologic effects of land use from a socioeconomic perspective : the case of Lam Phra Phloeng Watershed, Thailand | |
| Author | Wahid, Shahriar Md. |
| Call Number | AIT Diss. no.WM-08-02 |
| Subject(s) | Land use--Social aspects--Thailand--Lam Phra Phloeng Watershed Land use--Economic aspects--Thailand--Lam Phra Phloeng Watershed |
| Note | A dissertation submitted in partial fulfillment of the requirement for the degree of Doctor of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-08-02 |
| Abstract | South East Asia has experienced enormous land use changes in the form of deforestation and clearance for agriculture, urban development, and infrastructure development. Thailand is a case in point where inhabitants often established agriculture on cleared forestland under adverse soil and climatic conditions for short-term economic gains, which, in combination with unsuitable management regime, has severely degraded many watersheds. It is feared that landscape exigencies responsible for land degradation may also be responsible for changes in the hydrological regime. In this regard, this dissertation is undertaken to quantify the significance and magnitude of environmental and socioeconomic factors associated with degradation and changes in the hydrological regime of an upland watershed in Thailand. Organizationally, the dissertation comprises two interlaced topics - study on land use dynamics and estimation of water availability - which are initially treated separately. Overall land-water nexus is subsequently decomposed to implicate policies and institutions geared towards promoting an Integrated Watershed Development and Management (IWDM) strategy. First, the environmental and socioeconomic attributes of the 815 km² study watershed (Lam Phra Phloeng) are narrated and quantified to realize the land use dynamics, and provide a basis for hypothesis setting and selection of variables for land use modeling. Based on the heuristic observation that degradation in the watershed follows spatial heterogeneity of a set of environmental (land use, topography, geology, soil) and socioeconomic (population density, land tenure, education, access to institutional credit, availability of extension service and livelihood option) factors, it is argued that these factors may be used for empirical analysis of degradation. Data and information were collected from the watershed and secondary data repositories, and through analysis of remote sensing images. Relationship between land degradation and land use dynamics is geo-statistically modeled corresponding to the presence or absence of erosion (dependent variable). Binary spatial auto-logistic regression model with 19 categorical and continuous predictors and 2 auto-covariates classified 80.2% of land correctly in terms of occurrence of erosion and explained 53.2% of the total variation. Cultivation and dependence on agriculture for livelihood positively and significantly affect degradation. Lack of access to institutional credit and land titles significantly increased the probability of occurrence of degradation. On the contrary, education and social cohesion are negatively associated with the occurrence of degradation. The Relative Operating Characteristic (ROC) curve was used to measure the performance of the model. The calculated area under the curve (0.879) suggests that significant predictor variables in the model can be confidently used to forecast the likelihood of occurrence of degradation and thus has been used to spatially identify priority areas for intervention. The second analytical part of the dissertation applies landscape ecology principles and uses statistical methods to test for significant relationship between landscape factors that characterize the socio-environmental construction of. degradation and the ecological response variable (runoff). Runoff in the un-gauged watershed is estimated based on the Natural Resource Conservation Service's (NRCS) "Water Available for Runoff' equation. Digital image was analyzed to aid runoff Curve Number estimation. Two-way between-subjects analyses of variance to test for differences amongst the landscape factors indicate that whilst land tenure per se appears not to impact runoff, tenure differentiation affects land use decision and ultimately watershed hydrology. Field cropped areas are associated with higher runoff compared to forest and orchards implying the importance of promoting soil and water conservation practices. Degraded areas are associated with high levels of runoff. The strong spatial interplay (dependencies, feedbacks and impediments) of factors causing land degradation and changes in the hydrological regime illustrates that current segregated policies and institutions for natural resource management should be resolved using an inter-disciplinary and multi-sectoral watershed management framework in which all government line agencies and watershed dwellers would give their full support and sincere commitment. The management framework would need to be supported by technical strategies and tools to implement polices. The dissertation therefore supports the Thai Government's efforts to promote the sustainable management of land and water resources through the implementation of Integrated Watershed Development and Management (IWDM) strategies. The significance of the dissertation lies in adopting a reductionism paradigm (i.e. analyzing the complex system by scrutinizing the smaller constituents) in dissecting land-water nexus and bringing the water component into the land use planning narrative. The results provide essential benchmark from which other studies (e.g. field experiments) on long-term environmental outcomes and cause-effect relations can be referenced |
| Year | 2008 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-08-02 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand S.; |
| Examination Committee(s) | Routray, Jayant K. ;Clemente, Roberto S. ;Gupta, Ashim Das; |
| Scholarship Donor(s) | Danish International Development Assistance; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2008 |