THE LACK AVAIBALITY OF WATER
RESOURCES
KARST MOUNTAINS IN BINANGUN
DISTRICT- BLITAR
Kristin Puji Rahayu
State University of Malang
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.
Oleh Nor Aina Hayati (Program Studi Teknik
Lingkungan Universitas Lambung Mangkurat Banjarbaru)
