Impact of Future Climate Change on water availability in Kupang City

The 4th International Seminar Department of Environmental Engineering Department of Environmental Engineering, Institut Teknologi Sepuluh Nopember

Public Health Program Study, Medical Faculty, Udayana University

Proceeding ISEE 2013 ISBN 978-602-95595-6-9

Impact of Future Climate Change on water availability

in Kupang City

Willem Sidharno a, b *, Ali Masduqi a, Umboro Lasminto c a Dept.of Enviroment Engineering, Institut Teknologi Sepuluh November

bMinistry of Public Work Republic of Indonesia, Directorate General of Water Resources

c Dept.of Civil Engineering, Institut Teknologi Sepuluh November

* Corresponding author present address: Institut Teknologi Sepuluh November, Dept.of Enviroment Engineering,Indonesia

Email : [email protected]

Abstract

Climate change may affect the hydrologic system that can affect the availability of water. Kupang city is a city that is high temperatures and low rainfall, by making climate change SRES scenarios A1FI and B1, from the results of analysis found that the effect of climate change on temperature rise also led to increased evapotranspiration and result in increased precipitation. The effect can be calculated with F.J.Mock method, with the results of the analysis increased runoff and discharge in the watershed since the year 2013 to 2099. the increasing number of people each year, the need for water also increased, by using water demand scenarios of low, medium and high, combined with climate change scenarios, the analysis of the results indicated that the availability of water is more and reached 593.98 m3/second, but in April-October there is a shortage of water to -49 m3/second. This is due to the high water demand and population increase.

Keywords: Climate change, water availability, SRES, temperature, MOCK, water demand,.

1. Introduction

Global warming is clearly evidenced by the increase in the average temperature of the earth and ocean temperatures, widespread melting of snow and glaciers, and sea level rise earth, which has been observed and measured. Studies on the effects of anthropogenic climate change has found that the magnitude and frequency of intense rainfall is expected to increase during the century (Zachary, et al., 2012). Climate change has become a very important environmental issue, and one that will challenge management practices of existing water resources in many ways such as floods and droughts (Zhang, et al., 2012). From the results of existing research, climate change impacts will affect hydrological processes in the future (Qin Ju, et al., 2012). Climate change and land use patterns affect the management of the existing water and forcing water managers to develop new techniques of water management in response to changes in the environment (Philip, et al., 2012). It is expected that the availability of clean water that can be used in Central Asia, South Asia, East Asia, Southeast Asia will decline in 2050. In particular, the neighboring areas of the river will have serious consequences (Synthesis Report of the IPCC Fourth Assessment Report, 2007). In fact, the evidence of climate change has been found in various parts of the world in the last decade, and many researchers have shown an increase in the frequency and size of floods and droughts. In many countries in the world, various research has been actively conducted to evaluate the impact of climate change on water resources systems. Christensen et al. (2004) evaluated the impacts of climate change on water resources in the Colorado River basin. Meanwhile, according to (Negash, et al., 2012) from the results of simulations using climate change scenarios showed only a slight little change in surface runoff, the same is conveyed (Ahmad, et al., 2011) that the monthly streamflow on average approximately the same during the second period of the simulation results of the future. Future climate scenarios typically result in a decrease in mean river flows and greater variability, but the effect on the availability of water is not the same and varies in different regions of the river

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Willem Sidharno, Ali Masduqi, Umboro Lasminto


basin and water users (Ralph, et al., 2005). There is evidence that long-term climate change has changed the flow pattern of the river, especially during the spring and summer, and forecasts indicate these changes will continue and will affect the ability of the water supply system to meet the needs of the future given the changes (Lee, et al., 2011).

Climatic conditions in the city of Kupang has low rainfall and high temperatures. This causes Kupang city became one of the frequent water crisis. The purpose of this study is to see the impact of climate change on water availability in the city of Kupang with models of climate change SRES scenarios A1FI and B1 models combined with a demand for clean water needs of the population with a low rate (150 lt/sec), medium (175 lt/ sec) and high (200 lt/sec) since the year 2012 to 2099 on the hydrological conditions. According to each scenario, the results of the analysis will be used as input data to analyze the need and the availability of water for the city of Kupang predict the amount of water in the future for each scenario..

2. Methodology

Climate parameters such as temperature and precipitation is expected to change in the future and could significantly affect the water resources available (Anil, et al., 2012). Assuming that changes in precipitation and temperature hydrologic impacts of climate change, and as the temperature and precipitation ranges in the same area as the range expected in any scenario of climate change, only the temperature and precipitation changes on climate change is needed (Melissa, et al., 1999). To determine the changes in the climatic elements such as temperature and rainfall. Temperature and precipitation are two important factors that influence the hydrologic processes meteorologic (Li li, et al., 2008). The results have shown that long-term annual runoff volume on average decreased by using the A2 emissions scenario (Parrisa Sadat et al., 2013). Water resources is a major component of the natural systems that might be affected by climate change (Bou-Zeid and Fadel, 2002). This study uses two different scenarios based on models of the IPCC (Intergoverment Panel of Climate Change). This model was chosen because it has the data of the variables that will be examined in this study. The scenario used in this study is the scenario A1FI and B1 are taken from the SRES (Special Report on Emission Scenarios) issued by the IPCC. Each of these scenarios has a change of emphasis and socioeconomic scenarios different.

Climate Changes Projection

In this study will be used A1FI scenario that describes a future world with rapid economic growth, low population growth rate, and the incentives for excessive fossil fuel technologies. and the B1 scenario describes a convergent world, with a population growth similar to A1, but with a significant change in economic growth in the field of services and information. climate change is used to model the changes, which will affect the temperature and precipitation changes in the world in the future. The scenario used in this study were taken from the SRES (Special Report on Emissions Scenarios, 2000) issued by the IPCC are shown in Table 1.

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The 4th International Seminar Department of Environmental Engineering


Table 1. projected changes in temperature and precipitation scenarios SRES A1FI (highest emissions in the future) and B1 ( lowest emissions in the future), divided into three sections of time; 2013-2039; 2040-2069; 2070-2099.

Month

2010-1039 2040-2069 2070-2099

Temperature °C Precipitation % Temperature °C Precipitation % Temperature °C Precipitation %

A1FI B1 A1FI B1 A1FI B1 A1FI B1 A1FI B1 A1FI B1

DJF 0,86 0,72 -1 1 2,25 1,32 2 4 3,92 2,02 6 4

MAM 0,92 0,8 0 0 2,32 1,34 3 3 3,83 2,04 12 5

JJA 0,83 0,74 -1 0 2,13 1,3 0 1 3,61 1,87 7 1

SON 0,85 0,75 -2 0 1,32 1,32 -1 1 3,72 1,9 7 2

Source : (IPCC, 2007)

Hydrologycal Modeling

Hydrological impacts of climate change were evaluated with lumped hydrological model and analyzed in accordance with the characteristics of the spring flood and the average inflow. In general (Marie, et al., 2010). The variables used as reference calculations hydrology, water availability is a surplus of water and storage volume. Hirologi variable calculation is based on water balance models FJ Mock. To calculate the surplus water, required amount of daily evapotranspiration, so in this paper the calculation of evapotranspiration calculated by the Penman-Monteith equation. Model F.J. Mock deliberately used because it is considered suitable to the climatic conditions and environmental Indonesia (FAO, 1973). While the storage volume is calculated based on surplus water infiltration and assumptions which may occur.

WS = CH – Eto (1)

V = 1/2(K+1)I + K x Vn-1 (2)

(3)

Where: WS: water surplus ; V: volume storage ; K: constant CH type of soil runoff: rainfall (mm) ; Eto: evapotranspiration (mm / day) ; Rn: net radiation (MJ m-2 day-1) ; G: soil heat flux density (MJ m-2 day-1) ; T: average daily temperature (oC) ; u2: wind speed at 2 m height (m s-1) es: saturation vapor pressure (kPa) ; ea: actual vapor pressure (kPa) ; Δ: slope vapor pressure curve (kPa oC-1) ; γ: psychometric constant (kPa oC-1)

Demographic data is one of the most important factors in the process of preparing a plan, remember that every plan needs water intended for the benefit of themselves. Increasing the number of residents in geometry method from the year 2012 with a population of 658 346 thousand, up to the year 2099 with a population growth of 3.19%.

3. Result and Discussion

Before performing the analysis, first performed calibration between runoff and rainfall that occurred in the watershed in the city of Kupang and surrounding areas, so that the results of the analysis are expected to be like the real situation. From the calibration results indicated

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that the value of R is 0.9339, so that the calibration is acceptable. for rainfall and flow calibration results can be seen in the watershed figure 1 and figure 2.

Figure 1. Results of the calibration graphs rain and runoff

Figure 2. Graphs of the rain and runoff that has occurred

From the results of the data analysis carried out by the rain and temperatures in the city of Kupang since 1993-2012 using A1FI and B1 scenarios, then an increase in temperature since the year 2013 to 2099 with a maximum temperature occurred on the A1FI scenario in the year 2099 with an average temperature of 30.62 o C and the lowest temperature is at the mean temperature of the beginning before the simulation is 26.85 oC. For more details can be seen in Figure 3 and figure 4.

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Figure 3. Mean temperature change scenarios A1FI and B1

Figure 4. Monthly temperature chart and change

Of the temperature changes that occur using A1FI and B1 scenarios, it leads to changes in the average evapotranspiration of truth conditions with scenario B1 in June, representing a reduction of 4.8 mm / month to 2.94 mm / month. for more details can be seen in Figure 5.

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Figure 5. The average change in Evapotranpiration

From the analysis of rainfall using A1FI and B1 scenarios, then produce changes in average rainfall that has increased since the year 2039 until the year 2099 with maximum average rainfall in the A1FI scenario occurred in the year 2099 is 151.93 mm average rainfall, an increase of 8, 09%. Minimum average rainfall also occurred on the A1FI scenario of 138.64 mm of rain or the normal decline of 1%. While the B1 scenario experienced a constant increase since the year 2013 to 2099. For more details can be seen in Figure 6 and Figure 7.

Figure 6. Changes in average rainfall

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Figure 7. Average monthly rainfall

From A1FI and B1 scenarios are used, changes in runoff calculation method fjmock. showed that a decline in runoff in B1 scenario by 23.20% and an increase of 1.23% in A1FI scenario. To more clearly seen in the figure 8. And to effect changes in the runoff discharge 80% and 90%, showing not so big changes. However, by using scenarios of water demand levels low, medium and high, then there is a shortage of water in April-October with the peak of the water shortage occurred in 2070-2099 in reaching -49.73 m3/sec in normal climatic conditions and maximum availability of water 2013-2039 was the year that is 606.95 m3/sec in the B1 scenario. For more details can be seen in Figure 9a, 9b and drawing pictures 9c, for each scenario water demand and climate change effects.

Figure 8. Graphic changes in runoff scenario A1FI and B1

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Figure 9a. the average change in rainfall, discharge and water demand

Figure 9b. the average change in rainfall, discharge and water demand

Figure 9c The average change in rainfall, discharge and water demand

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4. Conclusion

From the results of the analysis, can be in the know that the effects of changes in temperature and rainfall effect on increasing evapotranspiration. The more the temperature rises then evapotranspiration ride. While the rainfall showed that promote increased rainfall runoff and discharge the year higher. So also with the increasing population and the need for increased water shortages caused high water in april to october. the general impact of climate change did not affect the availability of water, but with the increase in population and water demand increases, greatly affects the availability of water in Kupang city.

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Impact of Future Climate Change on water availability in Kupang City