Assessing the past and adapting to future floods: a hydro-social analysis

Devkota, Rohini Prasad; Bhattarai, Utsav; Devkota, Laxmi Prasad; Maraseni, Tek

doi:10.1007/s10584-020-02909-w

Cited by 31 publications

(31 citation statements)

References 42 publications

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“…The cross-section survey was conducted in 2014 by the Department of Water Resources and Irrigation (DoWRI), previously the Department of Irrigation. The same cross-section data were used by Devkota et al (2020) while analyzing floods across the study area. The Department of Hydrology and Meteorology (DHM) issues timely flood forecasts for the study basin using the same data by forcing hydrodynamic models, such as HEC-RAS and MIKE.…”

Section: Study Areamentioning

confidence: 99%

Assessment of vertical accuracy of open source 30m resolution space-borne digital elevation models

Talchabhadel

Nakagawa

Kawaike

et al. 2021

Geomatics, Natural Hazards and Risk

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Highly accurate air-borne Digital Elevation Models (DEMs) are not commonly available in most regions of the world, particularly developing countries like Nepal. Better topographic data are required to assess catchment hydrology, flood/inundation propagation, and sediment transport/deposition. Ground-based surveys (i.e., topographic and bathymetry) and Light Detection and Ranging (LIDAR) are expensive in terms of cost and time. We rely mostly on space-borne DEMs when the area of interest is quite large. And, for river cross-sections at specific regions, ground-based surveys are conducted at some regular intervals. The ALOS World 3 D À 30 m (AW3D30), ASTER Global DEM Version 3 (ASTER GDEM v3), SRTM-30, and Carto DEM v3 are some of the popular and latest space-borne DEMs that have been made available to the general public free of charge at a spatial resolution of 30 m. The availability of multiple space-borne DEMs may likely puzzle the practitioners on the selection of appropriate products. Here in this study, we evaluate the vertical accuracy of different space-borne DEMs with respect to the ground-based survey points (2891 points) at river cross-sections and ground-based indicative spot heights (8102 points) across the West Rapti River basin, Nepal. Performance metrics, like mean error and root mean square error (RMSE), were used to quantify deviation with respect to observed elevation. The AW3D30 showed the lowest RMSE value (i.e., 3.41 m) in the lower region of the study area. We numerically simulated the inundation propagation based on four selected DEMs using a calibrated two-dimensional runoff inundation model, and we find the AW3D30 outperforms other DEMs. All four DEMs showed a similar tendency on a catchment scale with respect to the information of indicative spot heights, suggesting interchangeable applications of all four DEMs in hydrologic analyses. However, precise ground-based observations across the catchment are needed for assuring the applicability.

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Section: Study Areamentioning

confidence: 99%

Assessment of vertical accuracy of open source 30m resolution space-borne digital elevation models

Talchabhadel

Nakagawa

Kawaike

et al. 2021

Geomatics, Natural Hazards and Risk

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“…Further, a 50-year period flood is a large flood with chances of significant damage -Scenario III. And finally, a 100-year period flood is a very large flood with high likelihood of extensive damage to life and property: it has been modelled as Scenario IV (details of the Scenarios and flood zones are available at Devkota, 2014, Devkota et al 2020.…”

Section: Methodsmentioning

confidence: 99%

“…There were 720 HHs in the three flood risk zones -144 in high; 274 in moderate; and 302 in low. Stratified random sampling with proportion of HH numbers was considered as a basis of allocating the sampling effort in each zone (Devkota et al 2020). Before administering HH survey and FGDs, the questionnaire was pre-tested.…”

Section: Methodsmentioning

confidence: 99%

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Conceptualising Flooding Systems Globally and Preferred Adaptation Strategies Locally under Climate Change

Devkota¹

2021

Jalawaayu

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Climate induced natural disasters and extreme events are escalating with the increased variability of climatic parameters due to climate change. This study assesses the flood adaptation strategies that are applicable at the community level in two Terai districts of Nepal. This research aimed to analyse existing and preferred future flood adaptation strategies in a flood prone West Rapti River (WRR) Basin of Nepal, and a social survey of 240 households (HHs) and focus group discussions (FGDs). The specific objectives were to identify flood adaptation strategies based on people’s perception. Flood inundation maps are generated for four scenarios based on return periods: Scenario I; Scenario II; Scenario III; and Scenario IV. Peoples’ choice of flood mitigation strategies mainly depends on the current needs of the people and their knowledge of harm. Current needs govern current choices while the basis of future choice is generally made on the degree of the impact or perceived risk of the hazard. This can be clearly seen from the ranking made by the people for Scenarios I and IV. “Household level preparation /management” was ranked first for Scenario I while in Scenario IV “Watershed management” was ranked highest. “Watershed management” was felt to be an important strategy, as it was second ranked even in Scenarios II and III. People may have realised that the mounting flood risk is increasing with time and that such risk can be reduced only through catchment management. When the risk is considered as of low level, people try first to adapt to it at the personal and household level. However, when the risk level increases, people look for alternatives or higher levels of adaptation. The perceptions of people in the study were found to be in agreement with these findings: as the flood risk increases from Scenario I to Scenario IV, the movement in choice of strategies changed accordingly. It can be concluded that when people are well-informed, they will do long term planning and formulate appropriate strategies. This research provides an overall framework for deriving potential mitigation and adaptation strategies to flood for Nepal in particular and other developing countries in general.

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“…but also in flood control works [9] [10]. Underestimation of the flows could lead to rejection of attractive projects whereas overestimation could have huge implications on the physical infrastructure and overall economic feasibility of the projects [4] [11]. Accurate flow estimates are, therefore, necessary at these basins where water resources projects are developed.…”

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confidence: 99%

Hydrological Modeling: A Better Alternative to Empirical Methods for Monthly Flow Estimation in Ungauged Basins

Marahatta¹,

Devkota²,

Aryal³

2021

JWARP

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Water resource is required for agricultural, industrial, and domestic activities and for environmental preservation. However, with the increase in population and growth of urbanization, industrialization, and commercial activities, planning and management of water resources have become a challenging task to meet various water demands globally. Information and data on streamflow hydrology are, thus, crucial for this purpose. However, availability of measured flow data in many cases is either inadequate or not available at all. When there is no gauging station available at the site of interest, various empirical methods are generally used to estimate the flow there and the best estimation is chosen. This study is focused on the estimation of monthly average flows by such methods popular in Nepal and assessment of how they compare with the results of hydrological simulation. Performance evaluation of those methods was made with a newly introduced index, Global Performance Index (GPI) utilizing six commonly used goodness-of-fit parameters viz. coefficient of determination, mean absolute error, root mean square error, percentage of volume bias, Nash Sutcliff Efficiency and Kling-Gupta Efficiency. This study showed that hydrological modeling is the best among the considered methods of flow estimation for ungauged catchments.

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Assessing the past and adapting to future floods: a hydro-social analysis

Cited by 31 publications

References 42 publications

Assessment of vertical accuracy of open source 30m resolution space-borne digital elevation models

Assessment of vertical accuracy of open source 30m resolution space-borne digital elevation models

Conceptualising Flooding Systems Globally and Preferred Adaptation Strategies Locally under Climate Change

Hydrological Modeling: A Better Alternative to Empirical Methods for Monthly Flow Estimation in Ungauged Basins

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