View from the river.

Uncertainty analysis of bias from satellite rainfall estimates using copula method

Reservoir Sedimentation: Assessment and Environmental Controls appraises the issues of sedimentation in reservoirs and discusses measures that can be employed for the effective management of sediment to prolong the operational life of reservoirs. It provides information for professional consultants and policymakers to enable them to manage dams in the best possible way, in order to ensure their sustainability as well as the sustainability of water resources in general. It examines the effects of anthropogenic intervention and management of sediment in dams and reservoirs, as water resources become more sensitive and the demand for clean water continues to increase.

Features:


Examines the issue of sedimentation in dams and reservoirs and presents water management strategies to alleviate environmental issues


Presents methods to help ensure the environmental sustainability of dams and reservoirs, as well as the sustainability of water resources- with consideration of climate change and increased demand


Illustrates the spatial distribution of sedimentation characteristics for several dams using geographic information systems (GIS)


Explains the relationships between loss in capacity and catchment characteristics


Examines regional variation in sediment yield, defines geomorphic regions on the basis of similar hydrometeorology, physiography, geology, and vegetation affecting reservoirs

Reservoir Sedimentation: Assessment and Environmental Controls

The Sample Analysis at Mars (SAM) instrument on board the Mars Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater. Central to this task is the development of an inventory of any organic molecules present to elucidate processes associated with their origin, diagenesis, concentration, and long-term preservation. This will guide the future search for biosignatures. Here we report the definitive identification of chlorobenzene (150–300 parts per billion by weight (ppbw)) and C2 to C4 dichloroalkanes (up to 70 ppbw) with the SAM gas chromatograph mass spectrometer (GCMS) and detection of chlorobenzene in the direct evolved gas analysis (EGA) mode, in multiple portions of the fines from the Cumberland drill hole in the Sheepbed mudstone at Yellowknife Bay. When combined with GCMS and EGA data from multiple scooped and drilled samples, blank runs, and supporting laboratory analog studies, the elevated levels of chlorobenzene and the dichloroalkanes cannot be solely explained by instrument background sources known to be present in SAM. We conclude that these chlorinated hydrocarbons are the reaction products of Martian chlorine and organic carbon derived from Martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources such as meteorites, comets, or interplanetary dust particles.

Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars

The moisture maximization approach to estimate the Probable Maximum Precipitation (PMP) has a simple technique for controlling the risk of overestimating PMP: the maximization ratio is limited by an upper bound. The upper bound limit depends on storm records and watershed characteristics. However, it is not readily available in many watersheds. A robust scientific justification for limiting the maximization ratio is missing. In this paper, a novel approach is proposed to estimate the maximization ratio which does not impose an upper limit to the ratio. The new approach, which uses regional climate model data, is based on constructing annual maximum precipitable water time series with precipitable water values for which atmospheric variables are similar to the original event to be maximized. These time series are then used to estimate the 100-year return period precipitable water value required to calculate the maximization ratio. The new approach was tested in three watersheds in the province of Quebec, Canada. Results showed that maximization ratio values were lower than the proposed upper bound value for these watersheds. In comparison to the approach using an upper bound, this proposed approach reduced PMP in these watersheds by 11%. This article is protected by copyright. All rights reserved.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016WR018603

A novel method to estimate the maximization ratio of the Probable Maximum Precipitation (PMP) using regional climate model output

Probable Maximum Precipitation Estimation for Catchments in Mahanadi River Basin

Effect of DEM source on equivalent Horton-Strahler ratio based GIUH for catchments in two Indian river basins

Cluster analysis based regionalization procedure is proposed to construct a regional envelope curve for use with Hershfield probable maximum precipitation (PMP) estimation method. The procedure suggests (1) delineation of the study area into homogeneous PMP zones (regions) by performing cluster analysis on attributes affecting PMP, and (2) construction of regional envelope curve for each of the zones, and use of the curve(s) as the basis to estimate regional frequency factor (RFF) and PMP for site(s) in the study area. Conventional practice suggests construction of a single envelope curve for entire study area, which could be a political/physiographic area, or a river basin. This practice could yield unreliable RFF and PMP estimates if there is considerable variation in topography, landscape and/or climate in the study area. Effectiveness of the proposed regionalization procedure is demonstrated through a case study on 0.25° resolution rainfall data covering India. Global K-means (GKM) and global fuzzy c-means (GFCM) methods are considered for cluster analysis. The number of delineated homogeneous PMP zones is 20 with GKM method and 17 with GFCM method. The PMP estimates obtained for 0.25° resolution grids using the proposed procedure are generally found to be lower than those obtained by considering (1) one/two envelope curves for the entire India determined based on zones considered in previous studies, and (2) envelope curves prepared for four major river basins (Mahanadi, Godavari, Krishna and Cauvery) in peninsular India. The PMP estimates are often considered as the basis to arrive at probable maximum flood (PMF) for design and risk assessment of large-scale hydrological structures in river basins. Hence, PMF estimates could be expected to be lower when based on PMP estimates obtained using the proposed procedure, which is likely to have economic implications in design of the structures.

Regionalization based envelope curves for PMP estimation by Hershfield method

This study investigated the multifractal characteristics of fine resolution (0.25ox0.25°) daily gridded rainfall fields of India over the period 1901–2013 to examine their spatiotemporal variability. The scaling characterization using Multifractal Detrended Fluctuation Analysis (MFDFA) detected short-term persistency and strong multifractality in the majority of rainfall (over 81%) of the grid points. A detailed exploration on the spatial variability of multifractal properties such as Hurst exponent, spectral width, asymmetry index, Holder exponent are also performed for six rainfall homogenous regions and 34 meteorological subdivisions in India. The results showed that the highest persistence and complexity is noted in the mountainous terrains of northern and northeastern India. The sub-divisional scale analysis showed that the variability of persistence and complexity is the highest in Kerala and lowest at Vidarbha. Further, the evaluation of multifractal properties of rainfall series of pre- and post-1976/77 Pacific climate shift showed an increase in strength of multifractality in 62% grids after the shift. Changes in the status of persistence with respect to 1976/77 is the highest at Uttaranchal subdivision and changes from positive to negative asymmetry was the highest at northwestern (NW) region. Grid points of Peninsular India exhibited least reduction in complexity, multifractality and persistence in the post-1977 period when compared to pre-1977 period.

Sagar Rohidas Chavan

Papers

Probable Maximum Precipitation Estimation for Catchments in Mahanadi River Basin

Effect of DEM source on equivalent Horton-Strahler ratio based GIUH for catchments in two Indian river basins

Regionalization based envelope curves for PMP estimation by Hershfield method

Spatiotemporal variability of multifractal properties of fineresolution daily gridded rainfall fields over India

Detection of abrupt change in trends of rainfall and rainy day’s pattern of Uttarakhand