Exceptional heavy rainfall over Ajoy, Mayurakshi and Kansabati catchments and QPF verification during flood season of September 2009

Ajoy, Mayurakshi, Kansabati are three important river catchments of West Bengal and Jharkhand state, received very heavy rainfall during two consecutive days of flood season in the month of September 2009. The contribution of heavy rainfall & combined discharges from Damodar Valley Corporation (DVC) reservoirs during the period of heavy rainspells over these catchments enhanced flood situation in some districts of West Bengal. The synoptic features based on weather charts, cloud imageries of satellite and radar pictures have been taken to analyse. The realized areal average precipitation (AAP) as per rainfall recorded at 0300 UTC of next day have also been taken to verify the quantitative precipitation forecast (QPF) of 6&7 September 2009.

Performance of IMD multi-model ensemble and WRF (ARW) based sub-basin wise rainfall forecast for Mahanadi basin during flood season 2009 and 2010

egkunh ds csflu esa 2009 o 2010 ds ck<+ ds ekSle ds nkSjku micsfluokj o"kkZ ds iwokZuqeku rFkk 2010 esa ck<+ ds ekSle ds le; izpkyukRed ¼9 fd-eh- × 9 fd-eh-½ fun'kZ ¼vkb-Z ,e- Mh-½ dk vkdyu djus ds fy, Hkkjr ekSle foKku foHkkx ¼vkb-Z ,e- Mh-½ ds izpkyukRed cgq&fun'kZ bUlSacy ¼,e-,e-bZ-½ ¼27 fd-eh- × 27 fd-eh-½ ds vk/kkj ij o"kkZ ds iwokZuqeku dk mi;ksx fd;k x;k gSA micsflu Lrj ij ,e-,e-bZ- vkSj MCY;w-vkj-,Q- ds dk;Z fu"iknu dk foLr`r v/;;u fd;k x;k gSA blls irk pyk gS fd lkekU;r% Hkkjh o"kkZ dh ?kVukvksa dks ekWMyksa }kjk de djds vkdfyr fd;k tkrk gSA Operational Multi-model Ensemble (MME) (27 km × 27 km) based rainfall forecast of India Meteorological Department (IMD) are utilized to compute rainfall forecast sub-basin wise for Mahanadi basin during flood season 2009 & 2010 and operational WRF (ARW) (9 km × 9 km) model (IMD) during flood season 2010. The performance of the MME and WRF at the sub-basin level are studied in detail. It is observed that generally heavy rainfall events are under estimated by the models.

Research and Application of Key Technologies for Dynamic Control of Reservoir Water Level in Flood Season

In today’s reservoir operation study, it is urgent to solve the issues on improving flood resource utilization, maximizing reservoir impoundment, and guaranteeing water supply through real-time regulation optimization under the premise of ensuring flood control safety and taking risks properly. Based on previous studies, the key real-time operation technologies for dynamic control of reservoir water levels in flood season are summarized. The Danjiangkou Reservoir was taken as an example, the division of flood stages, reservoir water level requirements for improving water supply guarantee, dynamic control indexes of reservoir water level for beneficial use in stages during the flood season, and flood control dispatching indexes are proposed. Moreover, a practicable real-time flood forecast operation scheme for Danjiangkou Reservoir was compiled. Its application in 2017 indicated that the established scheme can provide strong technical support to ensure the overall benefits of Danjiangkou Reservoir, including flood control, water supply, and power generation.

Quantitative Relationships between the Tidal Current Limit, Tidal Level Limit and River Discharge in the Changjiang River Estuary

Estuaries are areas where runoff and tide interact. Tidal waves propagate upstream from river mouths and produce tidal currents and tidal level variations along rivers. Based on the hydrological frequency analysis of river discharge in the dry season and flood season at the Datong hydrological station over the past 70 years, a three-dimensional estuary numerical model was used to produce the quantitative relationships between the tidal current limit, tidal level limit and river discharge in the Changjiang River estuary. The positions of tidal current limit and tidal level limit depend not only on river discharge but also on river topography. When river discharge varies from a hydrological frequency of 95% to 5%, the relationship between the tidal current limit and river discharge is y=2×10−13x3+3 × 10−8x2− 0.0074x+359.35 in the flood season, with a variation range of 90 km, and y=−4×10−10x3−1 × 10−5x2−0.1937x − 1232.9 in the dry season, with a variation range of 200 km. The relationship between the tidal level limit and river discharge is y=6×10−8x2−0.0096x+775.94 in the flood season, with a variation range of 127 km, and y=0.3428x2−17.9x+777.55 in the dry season, with a variation range of 83 km, which is located far upstream of the Datong hydrological station.

Using systems thinking to study the coordination of the water–sediment–electricity coupling system: a case study on the Yellow River

Joint operation of the Longyangxia and Liujiaxia reservoirs (Long-Liu operation) is of great significance for water and sediment regulation in the Yellow River. The water–sediment–electricity coupling system is a giant system with complex nonlinear relationships. A reliable Long-Liu operation scheme facilitates maximization of the benefits of the water–sediment–electricity system. Based on systems thinking, this paper quantitatively evaluated the reliability of different Long-Liu operation schemes and coordination of the water–sediment–electricity coupling system through the entropy weight method and dissipative structure model. The results indicated that the current operation scheme is more reliable than the adjusted scheme at the inter-annual scale and during the summer-autumn flood season and ice flood season within a year. However, the operation scheme should be improved during the spring irrigation period. The key factors influencing the quality of the water–sediment–electricity system include the outflow of the Liujiaxia reservoir, incoming sediment load into the Yellow River at Toudaoguai, sediment inflow-outflow difference in the Ningxia-Inner Mongolia Reach, water flow at Lanzhou and power generation upstream of Toudaoguai. The water–sediment–electricity system under the current Long-Liu operation scheme is more coordinated than that in the adjusted state, but the overall coordinated development of the system remains at a low activity level.