Erosion and flood mitigation in Jiadhal Basin using remote sensing and an ecosystem based disaster Risk reduction approach | |
| Author | Bormudoi, Arnob |
| Call Number | AIT Diss. no.DM-16-05 |
| Subject(s) | Ecosystem management Risk assessment |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Disaster Preparedness Mitigation and Management, School of Environment, Resources and Development - School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. DM-16-05 |
| Abstract | The Jiadhal River in the North East India is a hilly river known for its frequent change of course and flash floods. It carries high sediments and silts from the hills of Arunachal Pradesh and deposits them on the fertile lands in the downstream Dhemaji District in neighbouring Assam. The cause of this high sediment in the river is believed to be erosion and landslides in the upper basin due to rampant deforestation together with an increase in the incidences of high rainfall events. The agricultural lands once dumped with sands have to wait an average of two to three years before the farmers can grow paddy over it. This has caused the loss of livelihood of more than 150,000 people in the lower basin. The prime objective of this research was to find a way of mitigating the problem of erosion and flash floods. The challenge was to find a solution which would be low cost, local, sustainable and contain the elements which could provide a generic solution to almost all the tributaries in the North Bank of the Brahmaputra River facing a similar problem. The research methods utilized a physically based model E30 to estimate the amount of soil erosion occurring from the basin in different years. The choice of the model was based upon simplicity and the availability of the data on the ground. Since the basin has a large coverage and is situated in a remote area, Remote Sensing technology proved to be a very useful tool in gathering data at the basin level. It helped to pinpoint the areas undergoing erosion with different severity and prioritize an action plan to mitigate the hazard at the first place. The novelty of the research was in the utilization of this technology to identify such areas where Vetiver, a native grass known for its ability to prevent erosion and runoff could be grown and planted in the basin in an approach to mitigate the problem. The other originality of the research was the linkage of the outcome of the physical model to the feasibility of adapting Vetiver plantation as a sustainable ecosystem based DRR approach for the community. The model results showed that erosion at an average of 17.0 tons ha-1yr-1 was occurring for the four years of analyses in the basin. The whole upper basin falling in Arunachal Pradesh suffered the severe part of this erosion where the consequence was evident in the lower basin. The landcover analyses of the basin in the same years revealed that Agricultural Land had been lost during the flood years. The area under Grass Land increased 47.0 km2 during this period indicating a growth of grass over sand dumped areas by floods in previous years. The depletion of those lands were further evident in the fact that the Sandy Soil class increased from 191.2 km2 to 239.5 km2 in the lower basin within the period of analyses. Since these sandy soil areas in general were favourable for the production of Vetiver, with the use of Remote Sensing and GIS technology, suitable areas of 202.6 km2 were identified for setting up nurseries for Vetiver to grow at a commercial level. The research used and index based method named Livelihood Vulnerability Index to investigate the strengths and weaknesses of the affected communities in terms of their vulnerabilities from the disaster. Thereafter, their coping was measured in economic, structural and social terms. It showed that the two distinct communities in the lower basin were differently abled to cope with the disaster when it came to this comparison. This result was used to design a framework to engage them in cultivating Vetiver to make them self-sufficient from an economic point of view. It further proposed that Vetiver slips could be transferred and planted in the slopes of the upper basin in the erosion hotspots at a priority basis identified by use of Geoinformatics technology. In order to engage the communities to practice this, a legal and operational framework was suggested at the end. |
| Year | 2016 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. DM-16-05 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) + School of Engineering and Technology (SET) |
| Department | Department of Development and Sustainability (DDS) |
| Academic Program/FoS | Disaster Preparedness, Mitigation and Management (DM) |
| Chairperson(s) | Nagai, Masahiko; |
| Examination Committee(s) | Pennung Warnitchai ;Ahamd, Mokbul Morshed ;Sutat Weesakul; |
| Scholarship Donor(s) | Geoinformatics Center, AIT, Thailand ;Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2016 |