WATER RESOURCES

Group III

a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state (ice), and a gaseous state (water vapor or steam).

WATER

Water resources are sources of water that are useful or potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. The majority of human uses require fresh water.

A. Sources and Distribution of Water

Water is widely distributed on Earth as freshwater and salt water in the oceans. The Earth is often referred to as the "blue planet" because when viewed from space it appears blue. This blue color is caused by reflection from the oceans which cover roughly 71% of the area of the Earth.

97% of the water on the Earth is salt water. Only three percent is fresh water; slightly over two thirds of this is frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction present above ground or in the air.

Water Resources

A graphical distribution of the locations of water on Earth.

Rain Water- collects on the earth in the form of

surface water and underground water.

Sources of Water

Surface Water- Water present on the surface of the

earth in the form of oceans, rivers, lakes, ponds and streams is called surface water. The water in rivers and lakes comes from rain and melting of snow on mountains. Rivers flow into the sea.

River

Ocean

Stream

Lake

Ground Water- Fresh water stored underground in aquifers.- Most fresh water resources are stored here.- Aquifer area underground with rocks and gravel that have spaces where water can accumulate.

B. Rainfall and Streamflow Dependability, Probability Concepts Rainfall depths for specific durations and

streamflow peaks occurring during long period of time are stochastic variables and can be analyzed as such. Statistical and probabilistic analyses allow the development of probability statements or estimates related to the magnitude of certain events.

For the programming of irrigation supply and simulation of irrigation management conditions, the concept of dependable rainfall is often employed. Dependable rainfall is defined as the amount of rainfall which can be exceeded over a given location for a fixed number of years out of given total number of years.

For instance, the 80% dependable rainfall is normally used in calculating the capacity of storage reservoirs and of main irrigation canals. This dependable monthly or annual rainfall is the value that will be exceeded on the average four out of five years that is with a probability of exceedance of 80%. For drainage projects, the 20% dependable rainfall is usually adopted.

The rainfall in a given period is considered normal if the rainfall that fell within the period is 50% dependable, i.e., it will be exceeded on the average every other year.

Streamflow records may be extended in time for purpose other than curve improvement. A mean for some past month or year may be needed. This can be obtained by simple regression or by regression models with both streamflow and precipitation as independent variables.

Schneider (1961), Riggs (1964) and Martin (1964) proposed and evaluated several models for estimating monthly mean discharges for months outside the period of record from discharge at a nearby gauged site and from the monthly precipitation totals on the two sites. Carroon (1970) extended monthly flow records at many sites in the upper Colorado River basin by a graphical method. The reliability of such a regression estimate is indicated by the standard error.

Rainfall-runoff models which can account for the detailed disposition of rainfall may be used to extend streamflow records. These may be regression models in which runoff is related to storm magnitude, storm duration, and an index of antecedent soil moisture or digital computer models which model the land phase of the hydrologic cycle. Both types of models require several years of concurrent streamflow and hourly precipitation records for calibration their output.

Surface water and groundwater are not isolated components of the hydrologic system, but instead interact in a variety of physiographic and climatic landscapes. Thus, development or contamination of one commonly affects the other.

C. Surface water and Ground water Development

The Hydrologic Cycle

Groundwater is a hidden resource. At one time, its purity and availability were taken for granted.

Groundwater is the water that saturates the tiny spaces between alluvial material (sand, gravel, silt, clay) or the crevices of fractures in rocks.

Scientists estimate groundwater accounts for more than 95% of all fresh water available for use.

Approximately 50% of Americans obtain all or part of their drinking water from groundwater.

Nearly 95% of rural residents rely on groundwater for their drinking supply.

Some facts to consider...

About half of irrigated cropland uses groundwater.

Approximately one third of industrial water needs are fulfilled by using groundwater.

About 40% of river flow nationwide (on average) depends on groundwater.

The source of groundwater (recharge) is through precipitation or surface water that percolates downward. Approximately 5-50% (depending on climate, land use and many other factors) of annual precipitation results in groundwater recharge.

HOW SURFACE WATER CAN ‘FEED’ AN UNCONFIED

AQUIFER.

Losing streams.In some areas, streams literally

recharge the aquifer through stream bed infiltration. These are called losing streams.

One of the most commonly used forms of groundwater comes from unconfined shallow water table aquifers.

These aquifers are major sources of drinking and irrigation water. They also interact closely with streams, sometimes flowing (discharging) water into a stream or lake and sometimes receiving water from the stream or lake.

HOW UNCONFINED AQUIFERS CAN ‘FEED’ SURFACE WATER.

Gaining streams. An unconfined aquifer that feeds

streams provides the stream’s base flow. This is called a gaining stream. In fact, groundwater can be responsible for maintaining the hydrologic balance of surface streams, springs, lakes, wetlands, and marshes. This is why successful watershed partnerships take a special interest in the unconfined aquifer adjacent to the stream, lake or other surface water body.

Left untouched, groundwater naturally achieves balance—discharging and recharging—depending on hydrologic conditions. In fact, some streams are gaining streams at times and losing streams at other times.

ACHIEVING BALANCE

Water Quality in the Philippines ◦Water quality protection and operation

and maintenance of sanitation facilities are a collaborative undertaking of the Department of Environment and Natural Resources (DENR) through the Environmental Management Bureau (EMB), Department of Health (DOH), Department of Works and Sewerage System (DWSS).

D. Water Quality Considerations

The Philippine government aims to maintain the quality of its surface waters according to their best beneficial use. This is embodied in the DENR Administrative Order (DAO) No. 34, which classifies bodies of water according to the degree of protection required. Class AA and SA have the most stringent water quality for fresh surface waters and marine/coastal waters; and D and SD waters have the least stringent water quality for fresh surface water and marine waters, respectively.

Hot spots areas of surface water quality were assessed by province using Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD) as parameters.

Groundwater quality was assessed by using Total Dissolved Solids (TDS) and Coliform.

Saltwater intrusion was mapped based on National Water Resources Board (NWRB) data. Other hot spots were identified and rated on the basis of the objective of recovering the water quality of surface waters (rivers, lakes, and bays) for beneficial use, i.e., Class A (for fresh surface waters) for drinking, and Class SB ( for coastal and marine waters) for recreation.

Categories◦The parameters for water quality are

determined by the intended use. Work in the area of water quality tends to be focused on water that is treated for human consumption or in the environment.

Alkalinity, Color of water, pH, Taste, and odor. Dissolved metals and salts (sodium, chloride, potassium, calcium, manganese, magnesium). Microorganisms such as fecal coliform bacteria (Escherichia coli), Cryptosporidium, and Giardia lamblia. Dissolved metals and metalloids (lead, mercury, arsenic, etc.) Dissolved organics: colored dissolved organic matter (CDOM), dissolved organic carbon (DOC) Radon Heavy metals.

Human Consumption or Drinking Water Parameters

Physical Properties: Color, odor, temperature, solids (residues), turbidity, oil content, and grease content. Chemical Properties - pH - Conductivity - Dissolved oxygen (DO) - Nitrate - Orthophosphate - Chemical oxygen demand (COD) - Biochemical oxygen demand (BOD) - Pesticides Biological Properties Bacteriological parameters: coliforms, fecal coliforms, specific pathogens, and viruses.

Environmental Water Quality Parameters

www.wikipedia.org www.slideshare.net Google books GROUNDWATER & SURFACE WATER:

UNDERSTANDING THE INTERACTION

References:

Group 3Antioquia, GailCapistrano, GavinoBolivar, Kim JonahZamudio, PedroBarrameda, JoppetIbo, Maria LouisaDimaiwat, Reynaldo

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