Determination of Threshold Runoff for Flood Warning in Nepalese Rivers

Gautam, Dilip; Dulal, Khadananda

doi:10.5595/idrim.2013.0061

Cited by 23 publications

(28 citation statements)

References 3 publications

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“…Moreover, the estimated discharge during flooding is greater than that of the normal flow, as shown in the simulation of the 2014 Karnali floods. The Karnali River has many tributaries fed by snow melt, drops in altitude by approximately 7000 m, and passes through The DHM has established threshold water level gauge heights of 10 m and 10.8 m for warning and danger levels, corresponding to 201.64 m and 202.44 m a.s.l., respectively [67] (Table 3). The discharge recorded on 15 August 2014, was 21,700 m 3 /s, with an observed water level of 15.2 m at Chisapani gauging station; this illustrates the severity of flooding in the downstream reach of the river area, which leads on the river overflow from both its banks.…”

Section: Simulation Of the 2014 Flood Eventmentioning

confidence: 99%

A Model-Based Flood Hazard Mapping on the Southern Slope of Himalaya

Aryal

Adhikari

Zhou

et al. 2020

Water

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Originating from the southern slope of Himalaya, the Karnali River poses a high flood risk at downstream regions during the monsoon season (June to September). This paper presents comprehensive hazard mapping and risk assessments in the downstream region of the Karnali River basin for different return-period floods, with the aid of the HEC-RAS (Hydrologic Engineering Center’s River Analysis System). The assessment was conducted on a ~38 km segment of the Karnali River from Chisapani to the Nepal–India border. To perform hydrodynamic simulations, a long-term time series of instantaneous peak discharge records from the Chisapani gauging station was collected. Flooding conditions representing 2-, 5-, 10-, 50-, 100-, 200-, and 1000-year return periods (YRPs) were determined using Gumbel’s distribution. With an estimated peak discharge of up to 29,910 m3/s and the flood depths up to 23 m in the 1000-YRP, the area vulnerable to flooding in the study domain extends into regions on both the east and west banks of the Karnali River. Such flooding in agricultural land poses a high risk to food security, which directly impacts on residents’ livelihoods. Furthermore, the simulated flood in 2014 (equivalent to a 100-YRP) showed a high level of impact on physical infrastructure, affecting 51 schools, 14 health facilities, 2 bus-stops, and an airport. A total of 132 km of rural–urban roads and 22 km of highways were inundated during the flood. In summary, this study can support in future planning and decision-making for improved water resources management and development of flood control plans on the southern slope of Himalaya.

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Section: Simulation Of the 2014 Flood Eventmentioning

confidence: 99%

A Model-Based Flood Hazard Mapping on the Southern Slope of Himalaya

Aryal

Adhikari

Zhou

et al. 2020

Water

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“…Recent extreme flood events in WRR were reported in 1977WRR were reported in , 1981WRR were reported in , 1983WRR were reported in , 1989WRR were reported in , 1998WRR were reported in , 2006WRR were reported in , 2007WRR were reported in , 2009WRR were reported in , and 2012. The flood occurred in 1981 was reached to 100-year return period flood (Gautam and Phaiju 2013). The recorded flood damages of 2006 flood event are shown in Table 1.…”

Section: Introductionmentioning

confidence: 99%

“…The average rainfall for WRR basin is about 1,500 mm. The relative humidity fluctuates as low as about 60 % in May to above 90 % in January (Gautam and Phaiju 2013). The WRR covers approximately 6,450 km 2 of basin area and has the total population of approximately 1,046,000 (CBS 2001).…”

Section: Introductionmentioning

confidence: 99%

Community-based flood damage assessment approach for lower West Rapti River basin in Nepal under the impact of climate change

et al. 2014

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The West Rapti River (WRR), one of the dynamic and economically important basins of Nepal, was focused in this study to understand the impact of climate change in localized scale. The adopted methodology was a community-based field survey followed by a hydrological modeling to estimate present and future flood damages for households and agriculture. Flood disaster occurred in 2007 was simulated and discussed. Highresolution atmospheric general circulation model's precipitation outputs for emission scenario A1B were utilized with their bias corrections to obtain the precipitation patterns over lower WRR basin for Present and Future (2075-2099) periods. A conceptual hydrologic model was employed to obtain the time series of daily river runoffs for the above-mentioned time durations followed by frequency analyses for probable flood discharges of 25-and 50-year return periods. Flood inundation simulations of 50-year return period events for Present and Future were carried out with the rainfall-runoffinundation model followed by a flood damage assessment for household and agriculture based on the inundation simulation results, and field survey data over the target area and potential flood damages were discussed. Integration of hydrological modeling and socioeconomic approach to foresee potential flood damages was achieved, and the adopted damage assessment methodology was systematically explained. The total increments of household and agriculture damages due to climate change were estimated for Present as 1.80 and 1.95, and for Future, it was 2.40 and 2.27, respectively, compared to 2007 flood disaster. Future flood frequencies, intensities, and consequent damages in the area show a significant increment compared to the present situation despite limitations and uncertainties.

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“…Agricultural land and crops were affected even by small floods during the monsoon season as most of the agricultural lands are adjacent to or near the rivers; this is similar to observations reported in Gautam and Phaiju (). Furthermore, housing structures, particularly in densely settled areas, aggravate flooding as they also obstruct the water flow (Gautam and Dulal, ). During the monsoon season, houses and settlements in the study area inundated for up to 3 or 4 days.…”

Section: Resultsmentioning

confidence: 99%

Assessment of climate change impact on floods from a techno‐social perspective

Devkota

Bhattarai²

2015

J Flood Risk Management

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Effective adaptation measures require proper understanding of the impacts of climate change (CC) on the livelihood of the local people, especially the poor who are more vulnerable to CC. In this study, trend analysis of the climatic parameters (precipitation and temperature) was carried out using RClimDex complemented by household surveys and focus group discussions to assess perceptions of the local people towards CC, its indicators and effects in the West Rapti River Basin (WRRB) of Nepal. Observed increasing trend in the temperature throughout the basin and increasing precipitation trend in some parts of the basin while decreasing trends in others demonstrate a spatial variation of CC thus affecting livelihood of local people. Survey results in selected Village Development Committees of Banke and Dang districts within the WRRB showed that agriculture was the most vulnerable to such changes. People perceived increased frequency of heavy rainfall along with unusual rainfall pattern as major indicators of CC, which is likely to cause floods damaging agricultural and settlement areas. This research tried to quantify trends of climate parameters, and also identified and prioritised causes of floods and impacts based on the people's perception which help to design effective plans and programmes to reduce CC impacts. This interdisciplinary research provides an overall framework for deriving climate change impact analysis for a river basin in particular and other Nepalese river basins in general with similar socioeconomic, topographic, and climatic conditions.

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Determination of Threshold Runoff for Flood Warning in Nepalese Rivers

Cited by 23 publications

References 3 publications

A Model-Based Flood Hazard Mapping on the Southern Slope of Himalaya

A Model-Based Flood Hazard Mapping on the Southern Slope of Himalaya

Community-based flood damage assessment approach for lower West Rapti River basin in Nepal under the impact of climate change

Assessment of climate change impact on floods from a techno‐social perspective

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