The world’s big rivers and their floodplains were central to development of civilization and are now home to c. 2.7 billion people. They are economically vital whilst also constituting some of the most diverse habitats on Earth. However, a number of anthropogenic stressors, including large-scale damming, hydrological change, pollution, introduction of non-native species and sediment mining, challenge their integrity and future, as never before. The rapidity and extent of such change is so great that large-scale, and potentially irreparable, transformations may ensue in periods of years to decades, with ecosystem collapse being possible in some big rivers. Prioritizing the fate of the world’s great river corridors on an international political stage is imperative. Future sustainable management, and establishment of environmental flow requirements for the world’s big rivers, must be supported through co-ordinated international funding, and trans-continental political agreement to monitor these rivers, finance their continual upkeep and help ameliorate increasing anthropogenic pressures. To have any effect, all of these must be set within an inclusive governance framework across scales, organizations and local populace. Stressors such as large-scale damming, hydrological change, pollution, the introduction of non-native species and sediment mining are challenging the integrity and future of large rivers, according to a synthesis of the literature on the 32 biggest rivers.

Anthropogenic stresses on the world’s big rivers

Water and food security are the key challenges under climate change as both are highly vulnerable to continuously changing climatic patterns. Studies have predicted that the average global temperature may increase by 1.4–5.8 °C and there would be substantial reduction in fresh water resources and agricultural yield by the end of the 21st century. Approximately 75% of the Himalayan glaciers are on retreat and will disappear by 2035. Moreover in Africa (Sub-Saharan Africa) by 2050 the rainfall could drop by 10%, which would reduce drainage by 17%. Majority of the fresh water resources has already been depleted and there is reduction in agricultural production globally with escalation in population and food demand. Some of the prominent climate change impacts are, growing deserts, and increase in the magnitude of floods and droughts. An extreme decline in crop yields in arid and semi arid areas globally has caused food shortages and a manifold increase in food inflation. Countries of Africa, Middle East, Arab and Asia have close economic ties with natural resource and climate-dependent sectors such as forestry, agriculture, water, and fisheries. This manuscript highlights groundwater recharge by utilization of wastewater using the Soil Aquifer Treatment (SAT) method in irrigation and the significance and methods of artificial recharge of groundwater. This paper also presents easily and economically feasible options to ensure water and food security under climate change and recommend formation of effective adaptation and mitigation polices and strategies to minimizing the impact of climate change on water resources and irrigation.

Climate change and challenges of water and food security

River Ganga is considered sacred by people of India for providing life sustenance to environment and ecology. Anthropogenic activities have generated important transformations in aquatic environments during the last few decades. Advancement of human civilization has put serious questions to the safe use of river water for drinking and other purposes. The river water pollution due to heavy metals is one of the major concerns in most of the metropolitan cities of developing countries. These toxic heavy metals entering the environment may lead to bioaccumulation and biomagnifications. These heavy metals are not readily degradable in nature and accumulate in the animal as well as human bodies to a very high toxic amount leading to undesirable effects beyond a certain limit. Heavy metals in riverine environment represent an abiding threat to human health. Exposure to heavy metals has been linked to developmental retardation, kidney damage, various cancers, and even death in instances of very high exposure. The following review article presents the findings of the work carried out by the various researchers in the past on the heavy metal pollution of river Ganga.

Research on heavy metal pollution of river Ganga: A review

Pakistan is vulnerable to climate change, and extreme climatic conditions are threatening food security. This study examines the effects of climate change (e.g., maximum temperature, minimum temperature, rainfall, relative humidity, and the sunshine) on the major crops of Pakistan (e.g., wheat, rice, maize, and sugarcane). The methods of feasible generalized least square (FGLS) and heteroscedasticity and autocorrelation (HAC) consistent standard error were employed using time series data for the period 1989 to 2015. The results of the study reveal that maximum temperature adversely affects wheat production, while the effect of minimum temperature is positive and significant for all crops. Rainfall effect towards the yield of a selected crop is negative, except for wheat. To cope with and mitigate the adverse effects of climate change, there is a need for the development of heat- and drought-resistant high-yielding varieties to ensure food security in the country.

https://www.mdpi.com/2304-8158/6/6/39/pdf/1

Climate Change and Its Impact on the Yield of Major Food Crops: Evidence from Pakistan.

Fluoride contamination in water is a major problem across the globe, with health hazards such as dental and skeletal fluorosis. Most earlier studies are confined to local or regional scales. As the problem has serious socioeconomic implications, there is a need for a global perspective. Thus, here we review worldwide research for nearly a century on fluoride contamination in water. We investigated the distribution of fluoride contamination in water, its sources, mobilization and association. The major findings are: (1) Anomalous fluoride concentration in groundwater is mainly confined to arid and semiarid regions of Asia and North Africa. (2) The geogenic sources of fluoride in water are mainly fluorine-bearing minerals in rocks and sediments, whereas anthropogenic sources of fluoride in water are mainly pesticides and industrial waste. (3) Fluoride mobilization from geogenic sources is mainly controlled by alkalinity and temperature. (4) Fluoride occurrence in water is associated with ions such as sodium, arsenic chloride and bicarbonate. There are few associations of fluoride in water with calcium and magnesium.

Worldwide contamination of water by fluoride

Large scale emigrations from rural areas to urban areas and population growth have been uninterrupted and accelerating phenomena in parts of Ganga basin, where urbanization is increasing at an unprecedented rate. Urban agglomer- ation is causing radical changes in groundwater recharge and modifying the existing mechanisms. Majority of the cities are sited on unconfined or semi confined aquifers depend upon river water and groundwater for most of their water supply and disposal of most of their liquid effluents and solid residues to the rivers and ground. There has also been an inevitable rise in waste production. Drainage of surface water has been disrupted as the small natural channels and low lying areas have been in filled, often with municipal waste. Total water potential of the Ganga basin including surface water potential and ground water potential is around 525.02 km 3 and 170.00 km 3 respectively. Basin supports approximately 42% of the total population in India. Water tables are declining at approximately an average of 0.20 m per year in many parts of the basin and there is a trend of deteriorating groundwater quality. The demand of water has been increased many folds and most of the areas are highly reliant upon the groundwater to meet this increasing demand for water, but unfortunately degradation of groundwater both in terms of quantity and quality has deteriorated the situation. Studies shows that change in climate may increase temperature by 2t o 6 ◦ C and can reduce precipitation up to 16%, which could reduce the groundwater recharge by 50%. In densely populated Ganga basin urban drainage consumes a high proportion of the investments into urban infrastructure and needs integrated approach for the sustainable development of water management, water education regarding conservation and pollution caused by urbanization.

Impact of Urbanization on the Hydrology of Ganga Basin (India)

River Yamuna is one of the most polluted rivers of the India. It originates from Yamunotri glaciers in the lower Himalayas at an elevation of approximately 6387 meters. The barrages formed on the river are playing a major role in escalating the river pollution. River can be divided into five segments on the bases of hydro-logical and ecological conditions. Water quality of only one segment (Himalayan segment) meets the river water quality standards. Normally no water is allowed to flow downstream of the Himalayan segment (Te-jewala barrage) especially in the summer and winter seasons to fulfill the demand of water of the surround-ing area. Whatever water flows in the downstream of the Tajewala barrage is the untreated or partially treated domestic and Industrial wastewater contributed through various drains. The discharge of untreated domestic and industrial effluents have severely affected the quality of Yamuna River and now it falls under the category E, which makes it fit only for recreation and industrial cooling, completely ruling out the possi-bility for underwater life and domestic supply. Almost every year mass death of fishes is reported. Pollution levels in the Yamuna River have risen. Biochemical oxygen demand (BOD) load has increased by 2.5 times between 1980 and 2005: From 117 tonnes per day (TDP) in 1980 to 276 TDP in 2005. The Yamuna has been reduced to a small stream, draining industrial effluents, sewage, dirt and other toxic substances. There is an urgent need to take stringent measures to alleviate these pollution loads and save an ailing river.

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A River about to Die: Yamuna

Study of quaternary aquifers in Ganga Plain, India: focus on groundwater salinity, fluoride and fluorosis.

India is a vast country and is highly diversified in terms of natural resources and socio-economic setup. Moreover, its water resources are unevenly distributed in space and time. With increasing population and increasing aspiration for improved standard of living, there is an acute pressure on the demand and availability of water. Though the idea of interlinking of rivers is not a new concept in India, it had rather persisted long back as much as in other countries of ancient civilization. National Water Development Agency (NWDA) has given the real shape to the proposal of the interlinking of rivers of the country. In India the river-linking project in a sensible and scientific manner will not only allow the prevention of the colossal wastage of a vitally important natural resource, mitigate the flood and inundation by detaining flowing surface water of rainy seasons, but also ensure availability of water to drier areas; combating both flood and drought simultaneously. Moreover, this project will generate 34,000 MW of hydropower and irrigation of an additional 35 million hectares (135,135 square miles) of land. Though linking of rivers may initially appear to be a costly proposition in ecological, geological, hydrological and economical terms, in the long run the net benefits coming from it will far outweigh these costs or losses. However, in the absence of any definite international legal framework, Bangladesh has raised objections against the project. This paper aims at looking at this long-term plan, the project proposal, its involvement and impact not only on the states of India, India as a whole, but also on its neighbouring nations which are linked with India through the waterways, and share the common climatic conditions and economic status.

Anil Kumar Misra

Papers

Climate change and challenges of water and food security

Impact of Urbanization on the Hydrology of Ganga Basin (India)

A River about to Die: Yamuna

Study of quaternary aquifers in Ganga Plain, India: focus on groundwater salinity, fluoride and fluorosis.

Proposed river-linking project of India: a boon or bane to nature