The south west coastal zone of Bangladesh has been affected by rampant water logging due to vulnerable climate, silted rivers and stumpy terrain; and introduction of IWRM and TRM at some places of the zone has substantially safeguarded the circumstance. This study aims to assess the benefits achieved due to implementation of IWRM in parts of Khulna and Jessore districts, and investigate some technical aspects evolving TRM. Analyses have been carried out using satellite images, RS and GIS technology, Digital Elevation Model (DEM) and field investigations. A mathematical formulation has been made to assess rate of tidal sedimentation due to TRM and selection strategies of tidal basins. The study comes up with evidences of considerable advancements in regional livelihood i.e. flood resistance, cultivated lands, cultivable area, cropping intensities and food security due to IWRM. Moreover, the technical facts established on TRM would help planners to have vivid perception regarding the process.

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Background: Extreme rainfall events are enormously frequent and abrupt in tropical areas like the Jeju Island of South Korea, impacting the hydrological functions as well as the social and economic situation. Rainfall magnitude and frequency distribution related information are essential for water system design, water resources management and hydro-meteorological emergencies. This study therefore has investigated the use of L-moments approach for hourly regional rainfall frequency estimation so as to ensure better accuracy and efficiency of the estimation process from the usually limited data sets. Results: The Hancheon catchment was considered as the primary study domain and several best fitted statistical tools were used to analyze consecutive hour rainfall data from five hydro-meteorological stations (Jeju, Ara, Eorimok, Witsaeorum and Jindallaebat) adjacent to the area. The cluster analysis and discordancy measure categorized the Hancheon catchment in three regions (1, 2 and 3). Based on the L-moments heterogeneity and goodness-of-fit measure, Gumbel and generalized extreme value (GEV) distribution were identified as robust distributions for the study area. The RMSE ratios for the catchment were found as 0.014 to 0.237 for Gumbel and 0.115 to 0.301 for GEV distribution. The linear regression analysis of the different rainfall quantiles inferred r-square values from 0.842 to 0.974. Conclusions: The L-moments and other statistical information derived from the study can be useful for important hydrological design considerations in connection with flood risk management, mitigation and safety; whereas the methodological framework of the study may be suitable for other small scaled catchment areas with high slope.

Rainfall in Bangladesh exhibits persistent wet and dry anomalies associated with occurrence of floods and droughts. Assessing inter-annual variability of rainfall is vital to account these hydrological extremes in the design and operations of water systems. However, the inter-annual variability obtained from short record rainfall data might be misleading as it does not contain whole climate variability which signifies the utmost importance of stochastic rainfall models. Since the inter-annual variability and stochastic models have not been explored adequately for rainfall in Bangladesh, this study evaluated (a) the spatio-temporal variability of rainfall focusing on inter-annual variability, and (b) applicability of a stochastic daily rainfall model, referred as the Decadal and Hierarchical Markov Chain (DHMC) model. Daily rainfall data of 1973-2012 for 18 stations across Bangladesh were used to investigate the probability distributions and autocorrelations of rainfall, and the model performances. Results show a higher magnitude of inter-annual variabilities of rainfall depth (standard deviation 80-250 mm) and wet spells (standard deviation 4-6 days) in wetter months (June to September) across rainfall stations in the east region of the country. In contrast, higher rates of inter-annual variabilities (i.e., coefficients of variations) were observed in drier months across the west region. Spatially, the dry spells were observed consistent across the country. Monthly rainfall showed decreasing trend over the region from west to the middle part of the country, whereas monthly number of wet days showed increasing trend over the eastern part. The DHMC was found to preserve the observed variabilities of rainfall at daily to multiyear resolutions at all stations, except a tendency to underestimate the autocorrelation of monthly rainfall depth. Despite this limitation, DHMC can be considered as a suitable stochastic rainfall simulator for a tropical monsoon climate like Bangladesh.

A number of dams have been constructed across the Mahi River in Gujarat state. Lower reaches of Mahi River from Sindhrot dam, near Vadodara to Gulf of khambhat, in 176 km length, has been selected for the change analysis of bank line migration, erosion and sedimentation pattern. Satellite imageries (LISS III) from 1990 to 2016 and google earth images have been used in the analysis in GIS environment. The study indicated that the river reaches from Tithor to Sona Talavadi is currently under active erosion .It has been observed that area of erosion is more than deposition. Probably it is due to checking of the sediments by the dams located in the upstream. Migration of bank lines from 1990 to 2016 is maximum towards southern side in the central portion and in the northern side at the river mouth within the flood plain.