Unsupervised classification of saturated areas using a time series of remotely sensed images

The spatial distribution of saturated areas is an important consideration in numerous applications, such as water resource planning or siting of management practices. However, in humid well vegetated climates where runoff is produced by saturation excess processes on hydrologically active areas (HAA) the delineation of these areas can be difficult and time consuming. A technique that can simply and reliably predict these areas would be a powerful tool for scientists and watershed managers tasked with implementing practices to improve water quality. Remotely sensed data is a source of spatial information and could be used to identify HAAs. This study describes a methodology to determine the spatial variability of saturated areas using a temporal sequence of remotely sensed images. The Normalized Difference Water Index (NDWI) was derived from medium resolution Landsat 7 ETM+ imagery collected over seven months in the Town Brook watershed in the Catskill Mountains of New York State and used to characterize the areas susceptible to saturation. We found that within a single land cover, saturated areas were characterized by the soil surface water content when the vegetation was dormant and leaf water content of the vegetation during the growing season. The resulting HAA map agreed well with both observed and spatially distributed computer simulated saturated areas (accuracies from 49 to 79). This methodology shows that remote sensing can be used to capture temporal variations in vegetation phenology as well as spatial/temporal variation in surface water content, and appears promising for delineating saturated areas in the landscape

The Promise, Practice, and State of Planning Tools to Assess Site Vulnerability to Runoff Phosphorus Loss

Publication history: Accepted - 23 October 2017; Published online - 1 November 2017.Over the past 20 yr, there has been a proliferation of phosphorus (P) site assessment tools for nutrient management planning, particularly in the United States. The 19 papers that make up this special section on P site assessment include decision support tools ranging from the P Index to fate-and-transport models to weather-forecast-based risk calculators. All require objective evaluation to ensure that they are effective in achieving intended benefits to protecting water quality. In the United States, efforts have been underway to compare, evaluate, and advance an array of P site assessment tools. Efforts to corroborate their performance using water quality monitoring data confirms previously documented discrepancies between different P site assessment tools but also highlights a surprisingly strong performance of many versions of the P Index as a predictor of water quality. At the same time, fate-and-transport models, often considered to be superior in their prediction of hydrology and water quality due to their complexity, reveal limitations when applied to site assessment. Indeed, one consistent theme from recent experience is the need to calibrate highly parameterized models. As P site assessment evolves, so too do routines representing important aspects of P cycling and transport. New classes of P site assessment tools are an opportunity to move P site assessment from general, strategic goals to web-based tools supporting daily, operational decision

Grain refinement of deoxidized copper

This study reports the current status of grain refinement of copper accompanied in particular by a critical appraisal of grain refinement of phosphorus-deoxidized, high residual P (DHP) copper microalloyed with 150 ppm Ag. Some deviations exist in terms of the growth restriction factor (Q) framework, on the basis of empirical evidence reported in the literature for grain size measurements of copper with individual additions of 0.05, 0.1, and 0.5 wt pct of Mo, In, Sn, Bi, Sb, Pb, and Se, cast under a protective atmosphere of pure Ar and water quenching. The columnar-to-equiaxed transition (CET) has been observed in copper, with an individual addition of 0.4B and with combined additions of 0.4Zr-0.04P and 0.4Zr-0.04P-0.015Ag and, in a previous study, with combined additions of 0.1Ag-0.069P (in wt pct). CETs in these B- and Zr-treated casts have been ascribed to changes in the morphology and chemistry of particles, concurrently in association with free solute type and availability. No further grain-refining action was observed due to microalloying additions of B, Mg, Ca, Zr, Ti, Mn, In, Fe, and Zn (~0.1 wt pct) with respect to DHP-Cu microalloyed with Ag, and therefore are no longer relevant for the casting conditions studied. The critical microalloying element for grain size control in deoxidized copper and in particular DHP-Cu is Ag

Simulating current and future water resources development in the Blue Nile River Basin.

Agricultural water management (AWM) interventions in the Nile Basin are a key to improve agricultural production and productivity. AWM interventions can be categorized based on spatial scales, sources of water and type of technologies for water management in control, lifting, conveyance and application. Various combinations of these interventions are available in the Nile Basin. Successful application of AWM interventions should consider the full continuum of technologies in water control, conveyance and field applications. AWM technology intervention combined with soil fertility and seed improvement may increase productivity up to threefold. Similarly, data sets used from a representative sample of 1517 households in Ethiopia shows that the average treatment effect of using AWM technologies is significant and has led to an income increase of US$82 per household per year, on average. The findings indicated that there are significantly low poverty levels among users compared to non-users of AWM technologies, with about 22 per cent less poverty incidence among users compared to non-users of ex situ AWM technologies. The Nile basin has 10 major water control structures that are used for various purposes including irrigation, hydropower, flood and drought control, and navigation. The Water Evaluation And Planning (WEAP) model is applied to the Nile Basin, considering existing infrastructure, and scenarios of water use under current, medium term and Iong term. The major water use interventions that affect water availability in rivers are related to irrigation development. Accordingly, the irrigation areas of the current, medium-term and long-term scenarios in the Nile Basin are, respectively, about 5.5,8 and 11 million ha, with water demands of 65,982 million m 94,541 million m' and 127,661 million m respectively. The total irrigation water demand for the current scenario is lower than the Nile basin annual flow. The total irrigation water demand for the medium-term scenario exceeds the Nile mean annual flow marginally. The irrigation demands for the long-term scenario are considerably greater than the mean annual flow of the Nile basin, assuming the existing management practice and irrigation water requirement estimation of the countries. The river water would therefore will not satisfy irrigation water demands in the long term unless the irrigation efficiency is improved, water saving measures are implemented and other sources of water and economic options are explored

Application of a physically-based water balance model on four watersheds throughout the Upper Nile Basin in Ethiopia

In Abtew, W.; Melesse, A. M. (Eds.). Proceedings of the Workshop on Hydrology and Ecology of the Nile River Basin under Extreme Conditions, Addis Ababa, Ethiopia, 16-19 June 2008. Sandy, UT, USA: Aardvark Global Publishin

Modelling erosion and sedimentation in the Upper Blue Nile

In Abtew, W.; Melesse, A. M. (Eds.). Proceedings of the Workshop on Hydrology and Ecology of the Nile River Basin under Extreme Conditions, Addis Ababa, Ethiopia, 16-19 June 2008. Sandy, UT, USA: Aardvark Global Publishin

Blue Nile flow, sediment and impact of watershed interventions: case of Gumera Watershed

Paper presented at the Second International Forum on Water and Food, Addis Ababa, Ethiopia, 10-13 November 2008High population pressure, inappropriate agricultural policies, improper land-use planning, over-dependency on agriculture as source of livelihood and extreme dependence on natural resources are inducing deforestation, overgrazing, expansion of agriculture to marginal lands and steep slopes, declining agricultural productivity and resource-use conflicts in many parts of Blue Nile. Increased land degradation from poor agricultural practices and erosion results in increased siltation and the reduced water quality in the river basin. The rainfall, runoff and sediment are highly variable both in time and space. Poor water and land management upstream severely affect runoff characteristics and the quality of water reaching downstream. The result is a downward spiral of poverty and food insecurity for millions of people both within the upper catchment and downstream across international borders. Quantification of the erosion, sedimentation processes and evaluation of impacts of interventions are difficult tasks. This paper schematizes the Blue Nile Basin (BNB) at various spatial levels as micro watershed, watershed, sub-basin to basin. It considers a particular watershed to model runoff, sediment and impact of watershed intervention. The result shows that runoff can be reasonably simulated with calibration of R2=0.87 and validation of result of 0.82, and comparable sediment modelling results. The study also demonstrates, by undertaking spatial analysis using topographic, soil and land use parameters it is possible to identify the high sediment risk sub-watersheds. Impact of typical watershed intervention using various widths of vegetative filter and application on high erosion risk watersheds show reduction of sediment yield from 52% to 74

A water balance-based Soil and Water Assessment Tool (SWAT) for improved performance in the Ethiopian highlands

In Awulachew, Seleshi Bekele; Erkossa, Teklu; Smakhtin, Vladimir; Fernando, Ashra (Comps.). Improved water and land management in the Ethiopian highlands: its impact on downstream stakeholders dependent on the Blue Nile. Intermediate Results Dissemination Workshop held at the International Livestock Research Institute (ILRI), Addis Ababa, Ethiopia, 5-6 February 2009. Colombo, Sri Lanka: International Water Management Institute (IWMI).The Soil Water Assessment Tool (SWAT) is a watershed model widely used to predict water quantity and quality under varying land use and water use regimes. To determine the respective amounts of infiltration and surface runoff, SWAT uses the popular Curve Number (CN). While being appropriate for engineering design in temperate climates, the CN is less than ideal when used in monsoonal regions where rainfall is concentrated into distinct time periods. The CN methodology is based on the assumption that Hortonian flow is the driving force behind surface runoff production, a questionable assumption in many regions. In monsoonal climates water balance models generally capture the runoff generation processes and thus the flux water or transport of chemicals and sediments better than CN-based models. In order to use SWAT in monsoonal climates, the CN routine to predict runoff was replaced with a simple water balance routine in the code base. To compare this new water balance-based SWAT (SWAT-WB) to the original CN-based SWAT (SWAT-CN), several watersheds in the headwaters of the Abay Blue Nile in Ethiopia were modeled at a daily time step. While long term, daily data is largely nonexistent for portions of the Abay Blue Nile, data was available for one 1,270 km2 subbasin of the Lake Tana watershed, northeast of Bahir Dar, Ethiopia, which was used to initialize both versions of SWAT. Prior to any calibration of the model, daily Nash-Sutcliffe model efficiencies improved from -0.05 to 0.39 for SWAT-CN and SWAT-WB, respectively. Following calibration of SWAT-WB, daily model efficiency improved to 0.73, indicating that SWAT can accurately model saturation-excess processes without using the Curve Number technique

Hydrological process in the Blue Nile

In Awulachew, Seleshi Bekele; Smakhtin, Vladimir; Molden, David; Peden D. (Eds.). The Nile River Basin: water, agriculture, governance and livelihoods. Abingdon, UK: Routledge - Earthsca