Climate Change and Water Exploitation as Co-Impact Sources on River Benthic Macroinvertebrates

Climate change can affect freshwater communities superimposing on other major stressors, such as water exploitation, with effects still poorly understood. The exacerbation of naturally-occurring periods of low flows has been reported as a major hydrological effect of water diversions, with severe impacts on river benthic macroinvertebrate communities. This study aimed at assessing long-term modifications of low-flow events in a large lowland Italian river possibly associated to climate change and the effects of these events, intensified by water withdrawals, on benthic macroinvertebrates. A 77-year dataset on daily discharge was thus analyzed through Mann-Kendall test and Sen’s method to investigate modifications of the main hydrological parameters. Moreover, macroinvertebrates were collected during the low-flow periods that occurred from 2010 to 2015 at three sites downstream of water withdrawals, representing three different conditions of hydrological impairment. After assessing possible differences in taxonomical and functional composition between sites and impairment conditions, redundancy analysis and ordinary least squares regression were performed to link benthos metrics to environmental (hydrological and physico-chemical) characteristics. An increase in the duration of the low-flow periods and reduced summer flows were detected on the long term, and the magnitude of low flows was significantly altered by water withdrawals. These hydrological features shaped both structural and functional characteristics of benthic assemblages, highlighting the need for a more environmentally-sustainable water resource management in the current context of climate change.

Irrigated areas drive irrigation water withdrawals

A sustainable management of global freshwater resources requires reliable estimates of the water demanded by irrigated agriculture. This has been attempted by the Food and Agriculture Organization (FAO) through country surveys and censuses, or through Global Models, which compute irrigation water withdrawals with sub-models on crop types and calendars, evapotranspiration, irrigation efficiencies, weather data and irrigated areas, among others. Here we demonstrate that these strategies err on the side of excess complexity, as the values reported by FAO and outputted by Global Models are largely conditioned by irrigated areas and their uncertainty. Modelling irrigation water withdrawals as a function of irrigated areas yields almost the same results in a much parsimonious way, while permitting the exploration of all model uncertainties. Our work offers a robust and more transparent approach to estimate one of the most important indicators guiding our policies on water security worldwide.

Description of larvae of Eleotris perniger (Teleostei: Eleotridae) in transition from saltwater to freshwater from Montserrat, West Indies

Larvae of the Smallscaled Spinycheek Sleeper (Eleotris perniger) in transition from saltwater to freshwater were identified using COI and 16S gene sequences and the morphology and color pattern were then described. Available freshwater habitat for this species on Montserrat is minimal and continued existence is threatened by potential water withdrawals.

Water management in crop cultivation

In mediterranean countries, water is considered as the most basic assets for economic sustainability growth. For cultivation, water is not only essential but also essential in different sectors such as in industries and economic growth. It is considered as also an important component of the environment with significant impact on natural conservation and health. Around 70% of fresh water withdrawals goes to agriculture. The use of water within the sectors are very diverse and included mainly for irrigation pesticides and fertilizers application and sustain livestock. In India, agriculture is an important sector for sustenance and growth of Indian economy. Today, in the whole world, India is one of the largest producers of agricultural products. Several agricultural commodities like tea, coffee, oil seeds, fresh fruits, fresh vegetables, rice, wheat, spices etc. are considered as the major supplier from India. For crop and yards water, irrigation management involves the monitoring of water applications. It is especially important to monitor soil moisture in order to promote optimise crop yields without runoff percolated loss.

Assessing Water Withdrawals in Scarce-Data Transboundary Areas by Use of Dynamic Precipitation–Flow Relationships: The Case of the Hasbani River Basin

The present study proposes a nonstandard solution to the problem of assessing water withdrawals (AWW) in the scarce-data transboundary basin. The applied AWW method operates with the open-source available data on precipitation and river flow and thereby overcomes the usual restriction due to lack of data on shared water use in the Middle East. Analysis of dynamic precipitation-flow relationships enable to separate the effect of water withdrawals from the total decline of river flow under the decreasing precipitation. This study is the first which provides complete information (1972–2020) on water withdrawals from total, surface, and base flow of the Hasbani River (Lebanon). The resulting values that exceed by far earlier published estimates were confirmed by (i) indirect indices (area of irrigated land and population), and (ii) validation of the AWW method based on independent data on water use (Israel Water Authority). The study results are useful for water balance estimations, as well as for management of water resources in the Jordan River headwaters basin and in the entire Lake Kinneret Basin. The AWW method can be applied to other transboundary basins and enables historical and real-time monitoring of water withdrawals as a necessary database for settlement of riparian water relations.

Global scenarios of irrigation water abstractions for bioenergy production: a systematic review

Many scenarios of future climate evolution and its anthropogenic drivers include considerable amounts of bioenergy as a fuel source, as a negative emission technology, and for providing electricity. The associated freshwater abstractions for irrigation of dedicated biomass plantations might be substantial and therefore potentially increase water limitation and stress in affected regions; however, assumptions and quantities of water use provided in the literature vary strongly. This paper reviews existing global assessments of freshwater abstractions for bioenergy production and puts these estimates into the context of scenarios of other water-use sectors. We scanned the available literature and (out of 430 initial hits) found 16 publications (some of which include several bioenergy-water-use scenarios) with reported values on global irrigation water abstractions for biomass plantations, suggesting water withdrawals in the range of 128.4 to 9000 km3 yr−1, which would come on top of (or compete with) agricultural, industrial, and domestic water withdrawals. To provide an understanding of the origins of this large range, we present the diverse underlying assumptions, discuss major study differences, and calculate an inverse water-use efficiency (iwue), which facilitates comparison of the required freshwater amounts per produced biomass harvest. We conclude that due to the potentially high water demands and the tradeoffs that might go along with them, bioenergy should be an integral part of global assessments of freshwater demand and use. For interpreting and comparing reported estimates of possible future bioenergy water abstractions, full disclosure of parameters and assumptions is crucial. A minimum set should include the complete water balances of bioenergy production systems (including partitioning of blue and green water), bioenergy crop species and associated water-use efficiencies, rainfed and irrigated bioenergy plantation locations (including total area and meteorological conditions), and total biomass harvest amounts. In the future, a model intercomparison project with standardized parameters and scenarios would be helpful.

A global gridded monthly water withdrawal dataset for multiple sectors from 2015 to 2100 at 0.5° resolution under a range of socioeconomic and climate scenarios

<p>Future sector-specific water withdrawals at a temporal resolution capable of representing patterns in seasonality and a commonly used spatial resolution are an important factor to consider for energy, water, land and environmental research.  Projected water withdrawals that are harmonized with assumptions for alternate futures that capture socioeconomic and climatic variation are critical for many modeling studies on future global and regional dynamics. Here we generate a novel global gridded water withdrawals dataset by coupling the Global Change Analysis Model (GCAM) with a land use spatial downscaling model (Demeter), a global hydrologic framework (Xanthos) and a water withdrawal downscaling model (Tethys) for the five Shared Socioeconomic Pathways (SSPs) and four Representative Concentration Pathways (RCPs) scenarios. The dataset provides sectoral monthly data at 0.5° resolution for years 2015 to 2100. The presented dataset will be useful for both global and regional analysis looking at the impacts of socioeconomic, climate and technological futures as well as in characterizing the uncertainties associated with these impacts.</p>