Water Security最新文献

In India, artificial recharge (AR) of aquifers is considered a primary supply-side measure to combat the widespread over-exploitation of groundwater. As a major collateral benefit of rainwater harvesting (RWH) is aquifer rejuvenation, both rainwater harvesting and AR are planned and executed as a set of coherent interventions. The Central and state governments have brought in several schemes involving AR and RWH. Moreover, a number of researches are being conducted on how to select the sites for structure construction, the types of structure and their designs depending upon the local hydrogeology, groundwater flow regime, terrain condition and demand of water, and how they impact on resource rejuvenation and improvement in water quality. Various researches are also available on how such endeavors are translating into socio-economic benefits. The paper reviews the researches that have been done in India on these issues and related government policies and schemes under execution. The critical issues like source water availability for recharge, upstream-downstream conflicts, and the rising awareness of different demand-side interventions for sustainable management of groundwater resources have also been discussed.

Peak attenuation results in a gradual decrease of the peak discharge when a flood propagates in downstream direction. Peak attenuation occurs along all rivers, but is not equally strong on all rivers. The rate of peak attenuation depends on the river geometry, such as river slope, floodplain width and available storage areas (floodplain, wetlands and lakes). Along many rivers worldwide, measures have been taken that decrease peak attenuation and hence resulted in higher flood water levels and increased flood risk downstream. This paper shows the importance of considering peak attenuation in flood risk management. It also shows that construction of embankments may, contrary to what generally is expected, increase peak attenuation, but that this strongly depends on the height of the flood defences in combination with the discharges that pose the greatest threat to areas downstream. This is exemplified using the Meuse River in the Netherlands as a case study.

Forests are under pressure globally. How deforestation affects river flow is essential for water security in many regions. Here we conduct a meta-analysis of studies investigating this question in large basins of South America and show that different modeling approaches lead to opposite conclusions about deforestation effects on river flow. A widely used approach has been to use surface models while assuming that deforestation occurs only within the basin and does not affect precipitation. Alternative approaches consider that deforestation affects precipitation and is not necessarily bounded by the catchment area. While surface models generally indicate that deforestation will increase river flow in South American large basins, including deforestation effects on precipitation leads in most cases to the opposite conclusion.

Climate change is leading to increasing hydrological extremes and quicker shifts between wet and dry extremes in many regions. These extremes and rapid shifts put pressure on reservoir operations, decreasing the reliability of water supply, flood control and other reservoir benefits. Decision-makers across all levels, from reservoir operators to flood plain residents, turn to heuristics to simplify decisions when faced with complexity and uncertainty, resulting in cognitive biases or systematic errors in decision-making. While cognitive biases are not new, climate change is exacerbating their impact for two reasons: 1) heuristics, just as infrastructure, are based on experience with historic conditions; 2) fragilities created by these cognitive biases can go undetected until extreme events occur. If not acknowledged and managed, these cognitive biases can lead to catastrophic failures of reservoirs and other infrastructure. To minimize risk of such catastrophic failure, we propose a multi-level approach to flood and drought management, one that strikes a balance between centralized and decentralized approaches. Such an approach is better able to cope with uncertain and changing conditions because it creates overlaps and diversity, which can respond to a wide range of conditions and builds checks and balances that mitigate cognitive biases latent in various decision-making units.

The right to water and sanitation is recognized as fundamental to attaining all other rights. Despite the progress in access to water and sanitation in Low-and Middle-Income Countries (LMIC), women and girls are vulnerable to various forms of violence when meeting their water, sanitation and hygiene (WaSH) needs. The findings on WaSH related gender-based violence (GBV) in LMICs are fragmented, and thus may not be able to inform policies and interventions aimed at addressing vulnerabilities to WaSH related violence. This scoping review characterizes forms of WaSH related violence against women in LMICs. A review of 29 peer-reviewed papers emerging from a search in Scopus, Medline, Embase and Web of Science reveals four dimensions of WaSH-GBV: structural, physical, psychological and sexual. We observed that gender norms reproduce power relations that intersect with drivers of inequities, social exclusion and marginalization to shape patterns of violence. Based on these findings, we propose a conceptual framework showcasing how contextual factors produce and reinforce WaSH related gender-based violence. We reflect on the implications of these findings for policy and suggest the need for WaSH practitioners and researchers to evaluate and measure WaSH access beyond the Joint Monitoring Program (JMP) service ladder. Further research on WaSH-GBV is essential to facilitate global efforts on achieving the Sustainable Development Goals (SDGs) for gender equality (SDG 5); and ensuring access to water and sanitation for all (SDG 6).

Today India is the third largest dam building country in the world with over five thousand large dams. However, despite the significantly large expenditure, the actual area irrigated by canal has shown an overall decline since 1991. Today, more than 60% of India’s irrigation happens through groundwater. Evaluation reports by official agencies like Comptroller and Auditor General of India (CAG), and independent evaluations by civil society organizations have pointed out to the poor performance of dams during construction, operation and maintenance. Despite this, the narrative that the dams “play a vital role in providing overall water security to the country” has not been validated with help of a closer look at the empirical evidence on performance of dams in the academia.

To address this, we embark on a comprehensive socio-hydrologic review of evaluation studies to understand if large dams have in fact improved water security defined broadly (beyond just the canal command area). We ask two questions (i) What types of studies have been conducted? (ii) What do they collectively say about dams improving water security?

We find that while the engineers and experts have ex-ante promised water security through dams, the ex-post studies have highlighted several pathways through which dams adversely affect water security. They essentially highlight the tradeoffs between water security of different stakeholders and bring out the ‘losers’ that go unnoticed. Growing empirical evidence shows that despite massive investments, dams are unable to deliver on their promises. We argue that this repeated under-performance suggests that the inherent ‘social-technical’ nature of irrigation systems has not been internalized in the dam design process.

In the way forward, we have discussed the need to design and implement dams as socio-technical systems, need for empirical field-based ex-post research to establish factual evidence. Further, it must feed back into ex-ante water planning. Structured processes like shared vision planning can be used to negotiate competing normative claims.

Aquifers, major source of fresh water, are depleting in the several parts of the world and posing a threat for a long-term water availability. Managed Aquifer Recharge is one of the potential options to meet the challenge of water security and comprehensive characterization of aquifer system is its essential prerequisite. Aquifer system from soil to the deep aquifers, down to the depth of 200 m or more can be mapped now through advanced geophysical technologies, specially, by airborne transient electromagnetic method. This paper presents a brief description of aquifer characterization through Heliborne Transient Electromagnetic (HTEM) surveys in diverse hydrogeological settings comprising of crystalline hard rocks, sediments, basalts, and alluvium in India. The HTEM results from different geological terrains are compared with ground-based observations as well as with drilling logs to evaluate the efficacy of HTEM surveys. It is found that HTEM surveys rapidly provided 3D geometrical and electrical attributes of aquifers, which compare well with in-situ observations. The high resolution 3D information of hydrogeological settings can be appropriately utilized for sustainable management of groundwater resources by the stake holders, government departments and policy makers.