Load sediments quantification in Algerian North-West basins by ANN (Artificial Neurons Network) method

Due to the complexity of basins morphometric parameters and the hydroclimatic irregularity of the semi-arid regions of North Africa, solid transport has been still far from being clearly assessed. This study attempts to shed light on this problem; in order to conceive a global model for the suspended sediment load quantification, taking into account all stream waters of the North-West area of Algerian. The calculation is based on the use of the ANN artificial neurons network method, which has proven its success and its reliability in several fields of research. The collected data are measured in hydrometric stations of several basins, such as Cheliff, Tafna, Macta, and Oran’s basins. The results obtained using the ANN method are sufficiently reliable, the best correlations were obtained for each studied stream water exceeding 97% (specific model to each station), and 90% in the case of a global model characterizing for all studied stations, which allows the extracted model to give better estimation of the suspended solid flow rates for any measured liquid flow rate of the north-west Algerian basins

Morphometric Analysis and Prioritization of Watersheds for Soil Erosion Management in Upper Gibe Catchment

As morphometric investigation is connected to prioritization of watershed, morphometric analysis has got a significance role in light of soil and water conservation. In this study, an endeavour for the examination of point by point morphometric analyses of sub-basins was accomplished through the measurement of linear and shape parameters by using ArcGIS-9.3 software. Specifically, linear and shape morphometric parameters like stream length, stream order, drainage density, stream frequency, bifurcation ratio, Length of overland flow, basin perimeter, form factor, compactness coefficient, elongation ratio has been considered. The SRTM DEM (30 x 30 m) is processed for the delineation resulting in 61 sub-basins. The morphometric parameters which affect the soil erodibility are considered to organize the sub-basins and relegate positions on the premise of their association with erodibility to get compound parameter (Cp) esteem. Based on the value of Cp the sub-basin with the lowest Cp value was given the highest priority and then categorized the sub-basins into three classes as high, medium and low in terms of priority. Accordingly, high priority zone comprises 11 sub-basins, medium 19 and low 31 sub-basins. The sub-basins which are falling under high priority were a great deal more defenceless to soil disintegration and ought to be given high need for land preservation measures

Climate Change and Texas Water Planning: an Economic Analysis of Inter-basin Water Transfers

Panel models with random effects are used to estimate how climate influences in-stream surface water supply, municipal water demand, crop yields and irrigation water use. The results are added into TEXRIVERSIM, a state wide economic, hydrological, environmental and inter-basin water transfer (IBTs) investment model, through the objective function and hydrological constraints. A climate change related scenario analysis from the Global Circulation Models (GCMs)--Hadley, Canadian, BCCR and NCAR with SRES scenarios A1B, B1, and A2 indicates that inter-basin water transfers not only greatly relax water scarcity problems for major cities and industrial counties, but also create growth opportunity for Houston. However, while destination basins receive the benefits, source basins will experience dramatic reduction in in-stream flow and water flows to bays and estuaries. Climate change requires accelerated water development with more IBTs proving economically feasible depending on the GCMs and SRES scenarios.Climate Change, Inter-basin Water Transfers, Water Scarcity, Environmental Stream Flows, Environmental Economics and Policy, Q25, Q54, Q58,

Use of satellite data in runoff forecasting in the heavily forested, cloud-covered Pacific Northwest

The author has identified the following significant results. Satellite-derived snow cover data improves forecasts of stream flow but not at a statistically significant amount and should not be used exclusively because of persistent cloud cover. Based upon reconstruction runs, satellite data can be used to augment snow-flight data in the Upper Snake, Boise, Dworshak, and Hungry Horse basins. Satellite data does not compare well with aerial snow-flight data in the Libby basin

Scaling gridded river networks for macroscale hydrology: Development, analysis, and control of error

A simple and robust river network scaling algorithm (NSA) is presented to rescale fine‐resolution networks to any coarser resolution. The algorithm was tested over the Danube River basin and the European continent. Coarse‐resolution networks, at 2.5, 5, 10, and 30 min resolutions, were derived from higher‐resolution gridded networks using NSA and geomorphometric attributes, such as river order, shape index, and width function. These parameters were calculated and compared at each resolution. Simple scaling relationships were found to predict decreasing river lengths with coarser‐resolution data. This relationship can be used to correct river length as a function of grid resolution. The length‐corrected width functions of the major river basins in Europe were compared at different resolutions to assess river network performance. The discretization error in representing basin area and river lengths at coarser resolutions were analyzed, and simple relationships were found to calculate the minimum number of grid cells needed to maintain the catchment area and length within a desired level of accuracy. This relationship among geomorphological characteristics, such as shape index and width function (derived from gridded networks at different resolutions), suggests that a minimum of 200–300 grid cells is necessary to maintain the geomorphological characteristics of the river networks with sufficient accuracy

Forest influence on the surface water chemistry of granitic basins receiving acid precipitation in the Vosges massif, France

This study shows the influence of acid rain on the chemistry of surface waters in two small basins. The basins present similar altitudes and climates, only one is forested, and the forest decline has been clearly established. In both basins, rain water is polluted by acids (H+, so24-,N03). This acid input is neutralized in soils but the efficiency of that neutralization varies from one basin to another: (a) in the non forested basin, the alkalinity of surface water dominates the anionic charge, (b) in the forested basin, the strong acid anions still dominate the anionic charge of a just neutralized solution. The chemistry of surface water in the forested basin cannot be explained only by the incident rainfall and its partial evaporation. There appears to be a major input of pollutant through dry deposits in throughfall

Controls on dissolved organic carbon quantity and chemical character in temperate rivers of North America

Understanding the processes controlling the transfer and chemical composition of dissolved organic carbon (DOC) in freshwater systems is crucial to understanding the carbon cycle and the effects of DOC on water quality. Previous studies have identified watershed‐scale controls on bulk DOC flux and concentration among small basins but fewer studies have explored controls among large basins or simultaneously considered the chemical composition of DOC. Because the chemical character of DOC drives riverine biogeochemical processes such as metabolism and photodegradation, accounting for chemical character in watershed‐scale studies will improve the way bulk DOC variability in rivers is interpreted. We analyzed DOC quantity and chemical character near the mouths of 17 large North American rivers, primarily between 2008 and 2010, and identified watershed characteristics that controlled variability. We quantified DOC chemical character using both specific ultraviolet absorbance at 254 nm (SUVA254) and XAD‐resin fractionation. Mean DOC concentration ranged from 2.1 to 47 mg C L−1 and mean SUVA254 ranged from 1.3 to 4.7 L mg C−1 m−1. We found a significant positive correlation between basin wetland cover and both bulk DOC concentration (R2 = 0.78; p \u3c 0.0001) and SUVA254 (R2 = 0.91; p \u3c 0.0001), while other land use characteristics were not correlated. The strong wetland relationship with bulk DOC concentration is similar to that found by others in small headwater catchments. However, two watersheds with extremely long surface water residence times, the Colorado and St. Lawrence, diverged from this wetland relationship. These results suggest that the role of riverine processes in altering the terrestrial DOC signal at the annual scale was minimal except in river systems with long surface water residence times. However, synoptic DOC sampling of both quantity and character throughout river networks will be needed to more rigorously test this finding. The inclusion of DOC chemical character will be vital to achieving a more complete understanding of bulk DOC dynamics in large river systems

Geometry of River Networks II: Distributions of Component Size and Number

The structure of a river network may be seen as a discrete set of nested sub-networks built out of individual stream segments. These network components are assigned an integral stream order via a hierarchical and discrete ordering method. Exponential relationships, known as Horton's laws, between stream order and ensemble-averaged quantities pertaining to network components are observed. We extend these observations to incorporate fluctuations and all higher moments by developing functional relationships between distributions. The relationships determined are drawn from a combination of theoretical analysis, analysis of real river networks including the Mississippi, Amazon and Nile, and numerical simulations on a model of directed, random networks. Underlying distributions of stream segment lengths are identified as exponential. Combinations of these distributions form single-humped distributions with exponential tails, the sums of which are in turn shown to give power law distributions of stream lengths. Distributions of basin area and stream segment frequency are also addressed. The calculations identify a single length-scale as a measure of size fluctuations in network components. This article is the second in a series of three addressing the geometry of river networks.Comment: 16 pages, 13 figures, 4 tables, Revtex4, submitted to PR

Closing of the Krishna Basin: irrigation, streamflow depletion and macroscale hydrology

River basins / Physical geography / Climate / Stream flow / Hydrology / Rainfall runoff relationships / Evapotranspiration / Irrigation programs / Water allocation / Water transfer / Environmental effects / Water quality / India / Krishna River / Andhra Pradesh / Maharashtra / Karnataka