In 1854, Doctor John Snow indicated the importance of healthy water to a region when he took bold action to deal with a water pump on Broad Street in London. As cholera was taking a grip across the capital city, Snow's independent studies revealed a cluster of cholera outbreaks around the Broad Street area; the only people who were unaffected were a group of workmen who hadn't used the water pump. Doctor Benjamin Richardson, Snow's friend, wrote in 1858, that Snow had "fixed his attention on the Broad Street pump as the source and center of the calamity. He advised the removal of the pump handle as the grand prescription. The Vestry [the term used for a committee of members elected to administer the temporal affairs of a parish] was incredulous but had the good sense to carry out the advice. The pump handle was removed and the plague was stayed. There arose, hereupon, much discussion among the learned... but it matters little for the plague was stayed." (Quoted from Removal of the Pump Handle)
This shows one of the main problems with the health of water. Although the Broad Street pump was bringing up contaminated water from a well below the surface of the street, this story demonstrates the effect of water contamination on a region. Unhealthy water, whether from a well or a river brings diseases and illness, which can spread quickly and dramatically, soon becoming an epidemic. (In fact, Snow's research and work to remove the pump handle started the school of epidemiology.)
This is particularly true in poorer regions where there is little money or resources for effective water treatment. Some years ago during a holiday in Thailand, my wife and I witnessed locals swimming and urinating in the same stretch of river. The health risks here are obvious.
Rivers also support an enormous diversity of life by providing a range of habitats between aquatic and land ecosystems. River habitats include the river channels, the vegetation on river banks, the floodplains and estuaries and lakes. Each of these habitats includes a complex array of smaller habitats with different physical conditions. For example,
1. River channels have pools, riffles, debris dams, rocks, woody debris, river banks and benches;
2. Floodplains may have intermittent lakes, swamps, chains-of-ponds, debris piles and channel systems; and
3. River bank vegetation includes reeds, grasses, shrubs and trees;
Maintenance of this diverse range of habitats and the animals and plants depending on them is of key importance for healthy rivers.
Rivers are a key part of the total landscape and life in a region. With around 70% of the world's surface covered by water and no clear definition of what a river is, we can assume that if we take the oceans out of the equation, rivers account for a huge percentage of the globe's face because it's the rivers which link up waterways across countries and continents; and also act as outlets for the inland water into the seas and oceans. With this in mind, maintaining linkages means making sure that a river is part of the total landscape and it's not just regarded as a channel running though the land. Disruption of any of the linkages along a river, between a river and its banks and floodplains and between a river and groundwater sources will affect the health of a river.
The ecological processes operating within a river are important for maintaining its health and biodiversity. They include:
1. Ensuring the river has enough energy and nutrients to sustain its food chain;
2. Maintaining animal and plant populations through reproduction or regeneration, dispersal, migration, immigration and emigration (Some species have quite specific requirements. For example, some fish need specific flows before they will migrate and/or breed, water birds need particular flood durations and temperatures before breeding, and many plant seeds require flooding prior to germination);
3. Maintaining natural interactions between species such as predator-prey, host-parasite and competition relationships (changes to flow, river bank vegetation or species composition such as through the spread of an exotic species such as carp.
Healthy rivers provide a good source of free leisure and entertainment through a range of activities such as boating, canoeing and swimming. No-one would want to pursue these hobbies in polluted rivers where there's a risk of being ill or playing in smelly, stagnant water.
In some regions of the world, farmers use rivers for agricultural irrigation. River water is an important resource for effective and efficient farming practices and for a good crop harvest. Unhealthy rivers will therefore have a huge impact not only on health but also on the livelihood of farmers and local economies.
Worldwide demands for water are increasing and with industry also using river water for cooling or even washing away waste, the health of river water is important to many different groups, although as with farmers' fertilizer washing into the river system and polluting it, sometimes it's those who use it the most who also inevitably contribute most to its pollution.
In short, river health' is an ambiguous and vague term (according to an article in Freshwater Biology) and it's sometimes illustrated with the analogy of human health, but there are certain things which have an effect on the use of the water, its purity and the role of the river as part of its local environment. And it's not simply confined to river habitat but to local businesses, the local economy and the general health and wellbeing of the whole ecosystem as well as the general concerns of human health, aesthetic beauty and pollution.
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