N. Goel - Academia.edu (original) (raw)

Papers by N. Goel

This study is carried out with the objective of examining the effect of altitude on water availab... more This study is carried out with the objective of examining the effect of altitude on water availability estimates for the various sub-basins of the Chenab river basin (mean elevation of the basin is 3600 m), which is a snow-fed Himalayan river basin located in the western Himalayas. This basin covers all three Himalayan ranges, i.e. outer, middle and greater Himalayas. For this study, the daily flow data of 11 gauging sites varying from 14 years to 23 years in the Chenab river basin are utilised. The other important information related to the physiography, hydrology and meteorology, etc, for the region are derived from the available literature and maps. The daily flow data of nine gauging sites are utilised for developing the regional relationships for water availability computations. These relationships are tested over the remaining two gauging sites. The regional relationships are developed using three different approaches. These approaches include: (i) parameter regionalisation for individual gauged sites of selected probability distribution, (ii) regionalisation of dependable flows and (iii) parameter regionalisation for the region as a whole of the selected probability distribution. The different methods are compared and discussed in detail. It is observed that the flow for a given dependability increases with catchment area and decreases with altitude. The flows of the catchments at higher altitudes exhibit larger variability in comparison to the catchments at lower altitudes. The regional relationships are recommended for the use of field engineers.

A flood forecasting system has been developed using MIKE11 river-modeling software modules rainfa... more A flood forecasting system has been developed using MIKE11 river-modeling software modules rainfall-runoff (RR) [or Nedbor-Afstromnings model (NAM)], hydrodynamic (HD), and flood forecasting (FF) for the Jamuneswari river catchment of the northwestern part of Bangladesh. The 3-arc second shuttle radar topography mission (SRTM) digital elevation model (DEM) version 4.0 and the D8 method of ArcGIS9.3 have been used to delineate river network and catchment bounderies, which are required for MIKE 11 model setup. The European Centre for Medium-Range Weather Forecast (ECMWF) model-forecasted rainfall data have been used in MIKE 11 NAM-HD modules to increase the forecast lead time to 72 h. Errors in forecast results have been assessed by computing efficiency index, coefficient of correlation, volume error, peak error, and peak time error. Integration of the MIKE 11 HD module with the MIKE NAM module has improved the result by 10.84% for efficiency index, 20.7% for volume error, 25.61% for peak error, and 95.83% for peak time error. The MIKE 11 FF module was applied along with the integrated MIKE 11 NAM and HD modules to minimize error in the forecasted result. The efficiency index, volume error, peak error, and peak time error of the hindcast result, before updating by MIKE 11 FF, were calculated as 0.803, 0.505%, 2.58%, and 2 h, After updating by the MIKE 11 FF module, results were calculated as 0.989, −0.005%, 0.158%, and 0.00 h. Inputting the ECMWF-forecasted rainfall, the updated forecasting system determined the efficiency index, volume error, peak error, and peak time error as 0.92, 0.008%, 0.87%, and 0.00% for 24 h; 0.87, 0.231%, 0.507%, and 0.00 h for 48 h; and 0.84, 0.519%, and 0.000 h for 72 h. The steps for developing the flood forecasting system described in this case study are generic and can be applied under similar geographic conditions in other locations worldwide. In Bangladesh, decision makers will have more time to develop responses to imminent the flooding as a result of the increased forecast lead time provided by the analysis method described in this case study.