Hydrology...the sound of this word tells you it seems like a serious word, probably not used much in casual conversation. But in the world of water hydrology rings loud and clear. Here's why... Like the framing of a house, the properties, distribution, and circulation of water (hydrology) and the relief features of the earth's surface (geomorphology) help give environments their character. Simply put, hydrology determines the characteristics and 'personality' of your drinking water.
The quantity and timing of water flows influence many ecosystem parts and processes, including those with direct effects on human activities. Loss of topsoil, which can take millennia to replenish, has obvious implications for agriculture, and moving sediment can cause sedimentation in harbors and other facilities and can carry chemicals for long distances. High and low water flows have important implications for ecosystem health. Low water flows define the smallest area available to stream biota during the year, and high flows shape stream channels and wash out silt and debris.
Some fish depend on high flows for spawning. The timing of high and low flows affects the status of aquatic species as well as human water supplies and the flooding of farms, towns, and cities. Climate, dams, water withdrawals, and changes in land use all affect the flow of water. High and low flows for 867 streams and rivers with appropriate data (records between 1930 and 1949, and during the 1970s, 1980s, and 1990s) show little change from the 1970s to the 1990s.The same is true for the timing of high and low flows.
But there is one troubling bit of data...the number of streams with high flows well above their historic (1930 to 1949) rates rose markedly from the 1980s to the 1990s. This increase may be attributable, in part, to earlier droughts, but may also be linked to widespread changes in land use, which has a direct affect upon your water quality.
How? By Erosion.
Erosion can have significant effects on ecosystem condition. Wind and water erode soils naturally, changing the character of the landscape. Human activities such as development, road construction, timber harvesting, and agricultural practices that disturb the soil surface or remove anchoring vegetation increase the potential for erosion. Soil loss not only reduces soil quantity and quality but also can degrade water quality by carrying nutrients, pesticides, and other contaminants downstream. Sedimentation can raise costs to maintain reservoirs, navigation channels, and water treatment plants and can degrade habitat for aquatic organisms. All of these conditions have a profound affect upon the overall quality of source water as well as the methods used to treat them successfully.