Takahiro Sayama

Rainfall–runoff–inundation analysis of the 2010 Pakistan flood in the Kabul River basin

Abstract Pakistan has suffered a devastating flood disaster in 2010. In the Kabul River basin (92 605 km2), large-scale riverine and flash floods caused destructive damage with more than 1100 casualties. This study analysed rainfall–runoff and inundation in the Kabul River basin with a newly developed model that simulates the processes of rainfall–runoff and inundation simultaneously based on two-dimensional diffusion wave equations. The simulation results showed a good agreement with an inundation map produced based on MODIS for large-scale riverine flooding. In addition, the simulation identified flash flood-affected areas, which were confirmed to be severely damaged based on a housing damage distribution map. Since the model is designed to be used even immediately after a disaster, it can be a useful tool for analysing large-scale flooding and to provide supplemental information to agencies for relief operations. Editor Z.W. Kundzewicz Citation Sayama, T., Ozawa, G., Kawakami, T., Nabesaka, S. and Fukami, K., 2012. Rainfall–runoff–inundation analysis of the 2010 Pakistan flood in the Kabul River basin. Hydrological Sciences Journal, 57 (2), 298–312.

Numerical Simulation of 2010 Pakistan Flood in the Kabul River Basin by Using Lagged Ensemble Rainfall Forecasting

AbstractLagged ensemble forecasting of rainfall and rainfall–runoff–inundation (RRI) forecasting were applied to the devastating flood in the Kabul River basin, the first strike of the 2010 Pakistan flood. The forecasts were performed using the Global Forecast System of the National Centers for Environmental Prediction (NCEP-GFS) and were provided four times daily. Dynamical downscaling was also applied to the forecasts by the Weather Research and Forecasting Model (WRF), a regional model. The forecasts of the rainfall and inundation area were verified by comparing rain gauge–corrected Global Satellite Mapping of Precipitation (GSMaP) data and the observed indicator of an inundation map based on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The GFS predicted a sign of heavy rainfall in northern Pakistan 4 days ahead of the onset. However, most of the forecasts predicted it in wrong places, and only those performed after the rainfall onset predicted it in the accurate location. Down...

An emergency response-type rainfall-runoff-inundation simulation for 2011 Thailand floods

A devastating flood disaster occurred in Thailand in 2011. In case of such large-scale flooding, it is important to predict the dynamics of inundation on a near real-time basis for safe evacuation. To predict widespread inundation, where both rainfall-runoff from surrounding mountains and rainfall on floodplains contribute to the event, this paper applied a rainfall-runoff-inundation (RRI) model to the entire Chao Phraya River basin (160 000 km 2 ). Near realtime simulation was conducted for emergency responses with globally available dataset including satellite-based topography (HydroSHEDS derived from SRTM)andrainfall(TRMM3B42RT)duringthedisaster.Post-floodsimulation was also carried out with more local information. The RRI model was found capable of representing the peak inundation extent with an acceptable accuracy and correctly predicting a 1-month lasting inundation in the lower part of the basin. On the other hand, the prediction overestimated the river discharge by 40% and the inundation water level by 2 m mainly due to the neglect of the evapotranspiration effect. The post-flood simulation improved its accuracy by up to 10% for river discharges and 1 m for peak inundation water levels, but it did not lead to better agreement of flood extents with those based on the remote sensing. Further study is recommended to improve accuracy for modelling of spatial extent of flooding. Furthermore, sensitivity analysis with different input suggested what information should be prioritised for emergency response-type flood simulations.

Assessment of hydrological extremes in the Kamo River Basin, Japan

ABSTRACT A suite of extreme indices derived from daily precipitation and streamflow was analysed to assess changes in the hydrological extremes from 1951 to 2012 in the Kamo River Basin. The evaluated indices included annual maximum 1-day and 5-day precipitation (RX1day, RX5day), consecutive dry days (CDD), annual maximum 1-day and 5-day streamflow (SX1day, SX5day), and consecutive low-flow days (CDS). Sen’s slope estimator and two versions of the Mann-Kendall test were used to detect trends in the indices. Also, frequency distributions of the indices were analysed separately for two periods: 1951–1981 and 1982–2012. The results indicate that quantiles of the rainfall indices corresponding to the 100-year return period have decreased in recent years, and the streamflow indices had similar patterns. Although consecutive no rainfall days represented by 100-year CDD decreased, continuous low-flow days represented by 100-year CDS increased. This pattern change is likely associated with the increase in temperature during this period. EDITOR D. Koutsoyiannis ASSOCIATE EDITOR E. Gargouri

Benefits of flood-prone land use and the role of coping capacity, Candaba floodplains, Philippines

Socio-ecological benefits provided by floods and use of flood-prone land can be essential, particularly where livelihoods are tied to natural hydrologic cycles, for instance in many developing countries. We use a physically based rainfall-runoff model and remotely sensed data to characterize seasonal inundation in Candaba, Philippines. Through community surveys and focus groups, we identify strategies that allow residents to cope with floods and benefit from the use of flood-prone lands. We apply direct market pricing methods to assess seasonal land use benefits in flood-prone and dry villages. While primary benefits are associated with rice cultivation, we find that flood-prone communities adapt their livelihoods to seasonal inundation, for instance, by using land alternately for agriculture and wild catch fisheries during dry and wet seasons, respectively. Livelihood benefits in flood-prone villages (US

ANALYSIS OF LONG-TERM RAINFALL-RUNOFF-INUNDATION IN THE CHAO PHRAYA RIVER BASIN

2266/ha) were similar to benefits in non-flooded villages (US

How old is streamwater? Open questions in catchment transit time conceptualization, modelling and analysis

2746/ha). In flood-prone villages, mean benefits from wild fish capture (US

How much water can a watershed store

190/ha) are marginal to mean benefits from farming during the wet season (US

A new time-space accounting scheme to predict stream water residence time and hydrograph source components at the watershed scale.

1200/ha). However, the adaptive practice of wet season fisheries and dry season agriculture in flood-prone lands yields annual benefits (US

A SIMPLE SCALING CHARATERISTICS OF RAINFALL IN TIME AND SPACE TO DERIVE INTENSITY DURATION FREQUENCY RELATIONSHIPS

1754/ha) that are significant within the context of the local economy. We conclude that discounting benefits from direct flood-prone land use may misrepresent the socio-economic role of floodplains. Supporting benefits from floodplain use while targeting coping capacities may enhance resilience to seasonal flooding, livelihoods and ecosystem function linked to natural hydrologic processes.