GIS Based Study of the River Systems in Terai from Dhanusha to Rautahat

Project Description

The broad objectives of the study are to prepare a GIS based digital inventory of the river systems crossing Indo-Nepal boarder in the said study area. More specific objectives are:
• To gather basic technical and social data on the rivers and drains that cross Nepal India border in the specified districts;
• To assess historical flood events and their impacts on both local communities and natural regimes of those rivers and drains;
• To gather data and information on the encroachment and human intervention into the natural regimes of those river system on both sides of the border and their observed effects in chronological order;
• To analyze the above data and information; and
• To compile those data and information along with the results obtained from the analysis and to present them in the form of GIS based digital inventories.

Assignment Description

Major activities carried out under the study included the following: • Study coverage of the river systems crossing in Dhanusha, Mahottari, Sarlahi and Rautahat districts. In Dhanusha district, all the river systems will be included expect the Kamala River Basin which is at the border of Siraha and Dhanusha districts; and which has already been covered in the previous similar study. • Topographical maps of 1:25,000 scales, produced by the Department of Survey shall be used as the base maps and all rivers and drains that are shown in those maps with or without annotation shall be taken into account for the preparation of rivers and flood problems inventory. The rivers and drains, which are not showing or mission in the said maps, should also be explored and included by field verifications. • Procurement of digital topographical data from Department of Survey. All the digital topographical data required to cover the said portion of the study area will be supplied to the consultant by the RTP/DWIDP. Some of the digital data required for the said study will be procured by the RTP itself. However, all those digital data supplied to that particular consulting firm which will be awarded the contract, will have to be returned back to the RPT/DWIDP as soon as the said study is completed. • Updating the database associated with the digital maps with the identification of the river in the area and additional fields incorporating information collected during the study, such as precipitation record and discharge gazing station, flood disaster, population data and socio-economic information. • Survey of the rivers, drains and associated relevant structures at reconnaissance level only. Measurement and estimation of discharge of river / drains during the field visit. • Delineation of flood prone area of each of the rivers based on field enquiry and available documents; Changes in the river regime over time due to natural process and also due to human intervention and encroachment on either side of the border, Diagnostic analysis of the flood problems and prediction of the same in future due to ongoing natural and human activities etc. • The following themes are to be developed to incorporate the requirement of scope of works (but not limited to); • River Theme: Name(s) by which a concerned river or drain is called in Nepal and also on the Indian side and its location (both description and depiction on the base map); • Catchment theme: Catchments area with catchments delineation; in case of minor drains of which the watershed area can not be delineated from the topographical maps only, they should be delineated right in the field during survey • Precipitation Station Theme: Precipitation recording station within the catchments and discharge gauging sites (if any) and summary of records (in absence of these data as in the case of minor rivers and drains those of the nearest applicable precipitation recording station shall be included) • Hydrological Information Theme: Hydrological information such as frequency and magnitudes of floods based on the local inquiry, historical records and empirical approaches; • Flood Disaster Theme: Records of flood disasters and losses of lives and properties in the past in the bordering area (such information shall include VDC name, ward No. And village name also) • Socio-economic Theme: Data on population and other socio-economic information such as number of households, cattle population, major economic activities, education, health, communication and other infrastructure in the flood affected or likely to be affected in the bordering area within Nepal • Flood Prone Area Theme: Delineation and collection of information of flood prone area of each of the rivers based ion field enquiry and available documents. • River Regime Change Theme: Changes in the river regime over time due to natural processes and also due to human interventions and encroachment on either side of the border.