Indicators Of Hydrologic Alteration Software Research Articles

PairwiseIHA: A python toolkit to detect flow regime alterations for headwater rivers

The PairwiseIHA is an open-source toolkit written in Python that enables the user to quickly obtain the Indicators of Hydrologic Alteration (IHA) from inflow and outflow time series for headwater reservoirs. Specifically, the IHA metrics obtained from inflows (outflows) are considered as natural (regulated) and the differences are used to indicate how the magnitude, frequency, duration, timing and rate of change are altered by reservoir operation. It extends the functionality of the popular IHA software for analyzing concurrent inflows and outflows. The results of three case study reservoirs in California highlight that reservoir operation leads to considerable alterations in the five components of the flow regime. The findings on flow regime alteration are consistent across wet, normal and dry years. Overall, the PairwiseIHA can serve as an effective tool to investigate alterations in flow regime induced by human activities for water managers, scientists, natural resource agencies and water users.

WITHDRAWN: Ecological impact assessment of South Indian river basins by water graphics

Abstract Water is the lifeblood of the Earth, and exposure to water through river systems sustains most of earthly life. The health of the river is dependent on various factors such as quantity, quality, and timing of flow. The spectrum of river flow variability is an ecologically crucial component in a river ecosystem. This study carried out in the Thamirabarani basin, Tamil Nadu, India, from 1984 to 2008 and in the Meenachil basin, Kerala, India, from 1980 to 2017. The analysis done using the Indicators of Hydrologic Alteration software reflects the basins' ecological distress, which plagued with quality issues, siltation, and weed proliferation. The absence of ecologically relevant low floods and large floods can be associated with the river basins' ecological degradation.

Multiple drivers of hydrological alteration in the transboundary Srepok River Basin of the Lower Mekong Region

Human-induced changes in land and water resources adversely affect global hydrological regimes. Hydrological alteration of the natural flow regime is considered to have a significant damaging and widespread impact on river ecosystems and livelihoods. Therefore, understanding the hydrological alteration of rivers and the potential driving factors affecting such alterations are crucial to effective water resources management. This study analyses the impact of changes in land use, climate, and hydropower development on the hydrological regime of the Srepok River Basin in the Lower Mekong Region. The Lower Mekong Basin (LMB) in Southeast Asia is known for its agriculture, forests, fisheries, wildlife, and diverse natural ecosystems. Historical land use and climate change are quantified (utilising European Space Agency land cover and observed meteorological data) and correlated with the hydrological indicators using the Indicators of Hydrologic Alteration (IHA) software. Moreover, pre and post impacts on the hydrological regime by hydropower development are quantified using the Range of Variability Approach (RAV) in IHA software. The results reveal that land use, rainfall, and temperature affect different aspects of the hydrological regime, with corroborating evidence to support variation among the most correlated IHA and environmental flow component (EFC) parameters with the three drivers. The highest and lowest correlations among the IHA and EFC parameters under each driver are against land use (0.85, −0.83), rainfall (0.78, −0.54), and minimum and max temperatures (0.42, −0.47). Among the parameters, the fall rate has the most significant effect on hydrological alteration of all drivers. Hydropower development in the basin mostly affects the fall rate and reversal. Identifying the connection between these multiple drivers and hydrological alteration could help decision-makers to design more efficient and sustainable water management policies.

Impact assessment of climate change on environmental flow component and water temperature—Kikuchi River

The Japanese archipelago extends over a large distance from north to south exposed to the effects of climate change. The aim of this study was to assess the impacts of climate change on environmental components by using hydrological indicators. The future climate change in the region was initially projected using HadGEM2-ES and MICRO5 models in three 20-year periods (2021–2040, 2041–2060 and 2061–2080), considering two representative concentration pathways (RCP4.5 & RCP8.5). The Kikuchi streamflow was then simulated using Soil and Water Assessment Tool modelling for the baseline (1986–2016) and future periods. Finally, the magnitude, duration, timing, and frequency of extreme flows were analysed using Indicators of Hydrologic Alteration software. The results showed a decrease in discharge under both models; however, a 2 m3/s increase was predicted under HadGEM2-ES (RCP4.5) in 2041–2060. Changes in river flow affect habitat suitability in aquatic ecosystems, and might have further impacts if the effects of water temperature are also considered. In our case study, water temperature was predicted to increase by up to 4 °C by 2080. This phenomenon will change habitat suitability, because important environmental flow components, such as the peaks of high flows and large flood frequency, will also increase.

Assessment of Environmental Flow Requirements by Entropy-Based Multi-Criteria Decision

Environmental flow methodologies based on hydrological indices have increasingly evolved, because they play an important role in a riverine ecosystem management. Moreover, human activities, such as dams, in many basins have altered their natural hydrologic processes and they also change habitat for aquatic and riparian species. Decision making by echo-managers considering these multi-variables has been subjective. Therefore, to provide eco-managers with guidelines, an eco-index with entropy related to the probability density function (pdf) and Ordered Weighted Averaging (OWA) operator is been suggested in this study. The index was applied to Geum River in South Korea with 33 Indicators of Hydrologic Alteration (IHA) by Richter et al. (1998) through IHA software (TNC 2009). The objective of this paper is to outline an entropy-based hydrologic alteration assessment of biologically relevant flow regimes using gauged flow data. On the Geum River, dams have affected river flow measured at four stations and the eco-index suggests that more attention needs to be paid to the tributaries between Gongju and Gyuam stations. Echo-Index with maximum entropy and OWA operator reflects the effect of every parameter and helps with determination considering multi variables. In future more temporal and spatial information needs to be examined for ecosystem alteration.

EFCAM: A METHOD FOR ASSESSING ALTERATION OF ENVIRONMENTAL FLOW COMPONENTS

ABSTRACTThe environmental flow components (EFCs) are a set of 34 streamflow statistics computed by the Indicators of Hydrologic Alteration software, which are used for environmental flow assessments and developing environmental flow recommendations. The objective of this paper is to demonstrate a methodology for analysing and summarizing the alteration of EFCs, called the EFC assessment method (EFCAM). EFCAM uses non‐parametric rank‐sum statistical tests, sometimes in conjunction with per cent change, to produce ratings of alteration for each EFC statistic, for both central tendency and range of variability. These ratings are combined into summary indexes of alteration, by event type (extreme low flow, low flow, high‐flow pulse, small flood and large flood), flow characteristic (frequency, magnitude, duration, timing and rise/fall rates) and overall. EFCAM is demonstrated by analyzing typical patterns of EFC changes in 66 rivers across the United States where flow is altered by dams. The results reported here show that EFCAM is an effective method for efficiently summarizing flow alteration of ecologically relevant components of flows, and hence would be a useful addition to the Indicators of Hydrologic Alteration software. Results of this study show an overall trend towards compression of the hydrograph from above and below into a more limited overall range on these 66 rivers. The results shown here add to previous findings on dam impacts on river flows by separating out alteration in different segments of the hydrograph, and identify some patterns of alteration not previously reported. Although the version of EFCAM used here is believed to be appropriate for most situations, it is flexible and can be tailored to the needs of a particular project by including or excluding certain flow statistics or using a different weighting system. Copyright © 2013 John Wiley & Sons, Ltd.

FISH ASSEMBLAGES RESPOND TO HABITAT AND HYDROLOGY IN THE WABASH RIVER, INDIANA

ABSTRACTDetailed relationships between fish assemblages and habitat and hydrology variation are largely unknown for large rivers. We evaluated hydrology, habitat variation and fish assemblages at 28 sites on the Wabash River, Indiana, USA, during 2005–2008. We calculated hydrologic variation with the Indicators of Hydrologic Alteration software and tested for temporal hydrologic effects on habitat variation of substrate particle size, water depth and water velocity by reducing data into principal component axes that were tested for differences among years with ANOVAs. We then tested for effects of habitat and hydrology variation on fish assemblages with canonical correspondence analysis. These analyses showed significant relationships between hydrologic variation and local habitats, and hydrology and habitat variables had significant relationships with fish assemblage structure. Our Mantel tests resulted in significant concordance among hydrology, local habitat variation and fish assemblage structure, suggesting associations of these variables. These results supported strong connections for hydraulic control over habitat variation and subsequent effects on fish assemblages. Copyright © 2011 John Wiley & Sons, Ltd.

Tributaries influence recruitment of fish in large rivers

Abstract – Recent work demonstrates that tributary inputs are important community reorganisation points for river biota; however, no studies have examined the long‐term effects of tributary inputs on fish population dynamics. This study examines nearly 40 years of young‐of‐year (yoy) paddlefish recruitment data to investigate the hypothesis that tributaries influence mainstem fish population dynamics. We generated hydrological variables from daily mean flow data (1965–2007) from an impounded reach of the mainstem Missouri River and from the Niobrara River, a relatively unaltered tributary, using Indicators of Hydrologic Alteration software. Three multiple regression models using natural‐log transformed catch per unit effort (log cpue) as the response variable were created using (1) Missouri River‐only flow variables, (2) Niobrara River‐only flow variables and (3) Missouri River and Niobrara River flow variables. Flow variables from the Niobrara River explain a greater proportion of yoy paddlefish log cpue variability demonstrating that tributaries can positively impact fish population dynamics in altered rivers.

Application of the Indicators of Hydrologic Alteration Software in Environmental Flow Setting1

Abstract: River scientists are increasingly asked to provide recommendations about the amount and timing of water flows needed to support ecosystem health. The need for scientifically credible environmental flow assessments and the limited availability of resources to conduct in‐depth studies place a premium on methods that can be readily applied at low cost. The Indicators of Hydrologic Alteration (IHA) software program was originally developed by The Nature Conservancy in the 1990s to quickly process daily hydrologic records to enable characterization of natural water conditions and facilitate evaluations of human‐induced changes to flow regimes. The evolution of the IHA software is discussed, including recent revisions and additions to the IHA that have improved its utility in environmental flow‐setting processes. Drawing from holistic methodologies developed around the world, the ability to calculate characteristics of five components of flow important to river ecosystem health – extreme low flows, low flows, high‐flow pulses, small floods and large floods – has been added to the IHA. A practical advantage of these environmental flow components is that an environmental flow prescription based upon them can be readily implemented in most water management settings. Frequently used as a one‐time generator of flow statistics, the value of the IHA increases when used interactively with ecological models. A process for linking IHA output to an ecological model to explore flow‐ecology relationships within an adaptive management context is presented and demonstrated through its application on the Green River, Washington. The IHA used in conjunction with ecological models facilitates the creation and testing of flow‐ecology hypotheses, formulation of water and land protection or restoration goals, and development of a focused research and monitoring program, all important components of environmental flow‐setting processes.