THE LACK AVAIBALITY OF WATER RESOURCES

KARST MOUNTAINS IN BINANGUN DISTRICT- BLITAR

Kristin Puji Rahayu

State University of Malang

E-mail: kristinpujirahayu@rocketmail.com

ABSTRACT :  Karst is an area that relatively dry, less fertile and barren. But, karst aquifer is very good and karst hydrological system is impermeable Thats condition can make this area supply large amounts of water. This area be able to good absorb water but can store over a period of time. This study focused on the Binangun district. Binangun which is a karst area should have a supply of water. But in fact on this district are experiencing drought. It will be influenced by the use of water resources.

Keywords : water resources, aquifer, karst mountain, infiltration wells.

         

            Characteristics of Binangun district can be seen from aerial photographs formed with rough topography, lots of dots dissolving residual dome that has a regular pattern, streams irregular and truncated or disappear due to enter infiltration into the underground river, bright hue, sparse vegetation and the land has not been utilized.

            Karst mountain landform region has its own characteristics. Landform that develops in the mountains karts strongly influenced by the characteristics of lithology and climate conditions. "Landform is derived from the leaching process in the form of limestone that make up the former rounded limestone domes regular and uniform, and drainage holes are formed.” Adji said.

            Landform thus have an influence on the water potential, so that the distinctiveness of the geomorphology of the karst environment can be used as a basis to assess the condition of the water system. Water sources in the karst need to know the characteristics of quality in spatial and time. Aquifers can be interpreted as a geological formation that can store and groundwater flow in sufficient quantities on the conditions specified hydraulic gradient (Acworth, 2001). Simply means it is able to supply a well or spring water in a given period .. If karst formations can store and running it so that a well or spring water discharge has a significant, then it is good if the karst formations called an aquifer. Furthermore, the two extremes in the karst aquifer system is the conduit and diffuse almost absent in other types of aquifers (White, 1988). There are times when a formation is dominated by karst conduit system and also sometimes there are no hallways conduit but more developed diffuse system, so only have a very small effect on karst groundwater circulation. But, in general, a well-developed karst areas have a combination of both these elements.

Karst Regions as Natural Water Aquifer

            At first, the experts understand that karst is an area dry unproductive. This is caused by the physical properties that make up the limestone region is dominated by secondary porosity, lots of cracks and holes in the surface and is unable to store water for a long time. Rainwater flushed karst areas are believed directly descended down towards the water-saturated zone then flows to the output points to be spring water or thrown into the sea.

It is believed to be the cause why the karst area is always synonymous with drought and barren area. Karst further assessed only in terms of economic limstone, as a class-C minerals.

            The development of knowledge about karst apparently revealed that it is a good water aquifers, directly affect human life and the environment. Epikarst concept coined by karst hydrologist Mangin (1973) states that the existing limestone layer near the surface karst has the ability to store water over a period of time.

            The same was stated by Alexander Klimchouk (1979, 1981) that the near surface karst zone is the main zone of filler system (hydrology) karst and diffuse infiltration through the flow gap (fissure flow). Daritipe water flow in a vertical slit, Chernyshev (1983) later estimated that epikarst zone is located at a depth of 30-50 meters below the surface karst with varying thickness, usually 10 -15 meters from surface (Klimchouk, 2003).

            Based on the results of these studies it became clear that the karst region has a function that is much more important than just a mound of excavated materials C, which is a natural water aquifers which are crucial to the supply of hydrology for the surrounding area.

Karst Region As Flood Control

            The physical characteristic of limestone the constituent can make area have the ability to absorb and store rain water over a period of time. It is not separated from the role of the epikarst zone is a area that is able to store water in the body's most limestones.

The existence of epikarst zone located near the surface it is possible to get interference from human activities, one of which is the change in the form of land, both for the purposes of exploitation of limestone as well as for other purposes, such as building construction.

            Surface karst rocks peeled leaving a more solid and massive with few pores and cracks. So when it rains, rocks are no longer able to absorb water. Water that is not absorbed will much through the surface and potentially cause flash flooding, especially if the peel has an extensive land and a significant slope.

            Any land that has been pared karst, it takes a long time (thousands of years) to re-form and function epikarst layer first. It can be concluded, any damage caused to the surface karst is permanent and can not be rehabilitated again.

Karst mountain Water Resources

            Hydrologic system in general karst areas are impermeable, but there are gaps and fissures that became impermeable rock (or can be called secondary permeability), so rain water can get into the rock, forming a widening cracks, caves formed and fused between one another fracture finally happened underground river.

            Karst water aquifer consists of layers of limestone. different karst area hydrology of the hydrologic cycle in the areas of water absorption by the high ground. The uniqueness of this karst hydrology are difficulties and uncertainties of a layer (surface elements) in the form of limestone in the area of ​​water storage and river flow. In addition, in some karst aquifers are concentrated and highly heterogeneous permeability distributions, such as ground water drilling can be very risky. besides, pumping water in karst areas can lead to lower ground. In karst areas is usually to get a steady stream of water flows away far enough so rare, only a short distance from the productive wells. The combination of soil layer thickness is limited to the area of ​​karst and karst aquifers little porosity and permeability concentration makes karst aquifers more vulnerable to pollution because groundwater flow velocities are larger and lack of water absorption.

Efforts to Overcome Water Scarcity Karst mountain

Limited sources of water that occurred in Binangun district caused by several factors, namely drilling ground water regardless of the water abundance aspects properly and less see aspects of geography. Communities around the drilling groundwater wild at points that are considered to have the water resources therein. It will also damage the environment Binangun district itself.

Recharge wells will be able to cope with water scarcity in the Binangun district. Infiltration wells can accommodate water runoff when it rains arrive. Thus increasing the amount of water that goes into the ground. As more and more water into the ground through infiltration wells, soil pores will be filled with water and will prevent soil degradation.

In addition, when the drought comes the availability of water is not too down drastically so that the existing wells in the Binangun district still be in use.

CONCLUSION

With a system of karst hydrology impermeable area, can make karst area is an area that has a reserve of water resources is high. However, this should be aware of the heterogeneous distribution of karst aquifers makes this area has a high risk activity that can reduce the utilization of land surface that can lead to water scarcity, especially in Binangun district. Attempts to overcome this shortage is one of them making infiltration wells. Infiltration wells can increase the amount of water that enters the soil during the rainy season arrives. And when drought comes the availability of water is not too down drastically.

REFERENCES

Anonymous. 2011. Bentang Lahan Karst (Kaustic Landform). (online)

(http://pemimpinperadaban.blogspot.com/2011/09/bentang-lahan-karst-kaustic-landform.html, accesed on  21 November 2012)

Geomorfologi dan Hidrologi Karst.(File PDF)

Oleh Eko Haryono dan Tjahyo Nugroho Adji (Kelompok Studi Karst Fakultas Geografi UGM)

Aimyaya. 8 Manfaat Pembuatan Sumur Resapan. (online)

(http://aimyaya.com/id/lingkungan-hidup/8-manfaat-pembuatan-sumur-resapan/, accessed on 21 November 2012)

Jurnal Distribusi Sumber Daya Air Minum Di Daerah Karst.

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