Cooper Sarafin
Chemistry
5/2/15

Hydrologic Alterations due to Human Development and its Effect on Water Quality,
Biophysical Properties, and Biological Populations in Fresh Water Sources
I have chosen to write my paper on hydrologic alterations and their effect on water quality.
These alterations have changed how biological populations in substantial areas and the biophysical properties of our rivers and streams, created a negative environment for aquatic ecosystems and reducing the quality of our water.
Hydrology is the scientific study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability. I will delve into urbanization and the man made alterations to our environment that affect earth’s hydrology and ultimately our drinking water. I will discuss what some of these negative factors are, what their purpose is, and what they do to our environment. I will then proceed to explain the negative effects of these changes.
Humans are a selfish species. We are consumers, we take what we need without much thought for the things or places we take them from. We alter the very place(earth) on which we are able to exist. In doing so we change its physical being. Our changes to our water supply, such as lakes, streams, and the sea have a large impact on hydrology and global drinking water. The most common structure that we humans build are probably dams. We build dams for a variety of reasons. For domestic water supply, to change the flow of a river, and for irrigation purposes to name a few.
Vorosmarty et al(1997) demonstrated that river’s runoff was dramatically aging , due to the growing population of global large dams, which has lead to biophysical changes in river systems. In 1994 it was determined by Dynesius and Nilsson that 77% of the total discharge of the 139 largest river systems in the northern third of the world were affected by river fragmentation; due to dams, reservoirs, inter catchment diversions, and irrigation. All of which could dramatically affect biological populations in a substantial area. Dams have been proven in a variety of studies to be a primary destroyer of aquatic habitats and have caused the extinction of several species. This has created a loss of ecosystem services on which human economy depends. The deterioration of terrestrial environments, associated water services and the dewatering of rivers leads to impaired water quality because point and nonpoint pollution can not be diluted. Reservoirs behind these large dams has created water storage that represents a 700% increase in the standing stock of natural water. The age of river water has

likely tripled well over one month. This can lead to changes in sediment transport and the reoxygenation of surface water.
Now lets move on to stream channelization. This refers to several kinds of channel modifications, usually built to provide flood protection to nearby settlements of people. Its intended purpose is to move the floodwater downstream more quickly. This is designed to prevent rivers over flowing into their flood plains. These have negative effects on the environment, which creates a higher probability of floods downstream and leads to more erosion. These channels are usually dug out with heavy machinery. These machines destroy the habitats of cold water species and their food, creating a bad living environment for them. The companies who take on these projects also tend to cut down trees near the shore for there heavy machinery to be able to reach this location, which then increases the water temperature through thermal pollution.
Hydrologic impacts due to urbanization and human development have been reported to cause water quality problems. Sedimentation(the tendency for particles to settle out of the fluid), increased temperatures, habitat changes, and the loss of fish populations. Dissolved oxygen is a key part of river
ecosystems.