[ABSTRAK
Perubahan iklim merupakan isu yang sedang dihadapi oleh masyarakatglobal, yang dipengaruhi oleh variabilitas curah hujan dan suhu udara. Penelitianini di lakukan di wilayah sungai Nasal-Padang Guci, dengan menganalisatrendline curah hujan dan suhu udara, selama kurun waktu 1910-2010, sehinggadiketahui pengaruhnya terhadap neraca air. Penelitian ini menggunakan metodeMann Kendall Test untuk mengetahui kecendrungan trendline nya, serta metodeNeraca Surplus Defisit untuk menganalisa neraca airnya. Dari hasil analisadidapatkan bahwa suhu rata-rata bulanan naik sebesar 0,80C selama 54 tahun,sedangkan kenaikan curah hujan pada tahun 1910-1978 sebesar 20 mm/69 tahun,dan meningkat selama tahun 1979-2010 sebesar 125 mm/30 tahun. Kenaikancurah hujan dan suhu udara mempengaruhi ketersediaan dan kebutuhan air di WSNasal-Padang Guci, dalam hal ini ketersediaan air dipengaruhi oleh curah hujandan evapotranspirasi yang merupakan fungsi dari suhu, sedangkan kebutuhanairnya dipengaruhi oleh tataguna lahan dan jumlah penduduk. Dari perhitunganneraca air diketahui bahwa ketersediaan air sungai pada tahun 2030 lebih kecildibandingkan dengan 2010, hal ini disebabkan karena pengaruh peningkatan suhuudara, sehingga nilai evaporasinya semakin besar. Ketersediaan air pada tahun2010 sebesar 3358,4 juta m3/tahun, sedangkan kebutuhan air untuk irigasi 669juta m3/tahun (20%), RKI (rumah tangga, perkotaan dan industri) sebesar 87,2juta m3/tahun (3%), dan sisanya 2602,2 juta m3/tahun (77%), tidak dapatdimanfaatkan. Ketersediaan air pada tahun 2030 menurun dibandingkan dengan2010 yaitu sebesar 2498,9 juta m3/tahun, untuk irigasi sebesar 1133,7 jutam3/tahun (45%), RKI sebesar 136,5 juta m3/tahun (4%), sedangkan sisanya1228,8 juta m3/tahun (51%) tidak dapat dimanfaatkan. Pada tahun 2010 air masihbisa mencukupi kebutuhannya dan terjadi defisit pada tahun 2030, yaitu padabulan Agustus dan September, sehingga diperlukan bantuan waduk untukmenyimpan air pada saat surplus, yang nantinya bisa digunakan kembali pada saatdefisit.

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ABSTRACT
Climate change is a global issue that is currently being faced by the globalcomunity, which is strongly influenced by precipitation and air temperaturevariability. The research examines the increase rainfall and air temperature, duringthe period 1910-2010 in the Nasal-Padang Guci River Area, and its influences onwater balance. The study uses Mann Kendall Test to determine the trend line ofprecipitation and air temperature, The methode used water surplus and defisit toanalyze water balance. The temperature rise of 0,80 C/54 years on the average.Rainfall in the year 1910-1978 increase by 20 mm/69 years, this is consideredreasonable, and does not have any significant effect. However increasessignificantly in the year 1979-2010 it amounted to 125 mm/30 years. The increaseof precipitation and air temperature variability affects water availability and waterdemand, in the Nasal-Padang Guci river area, in this case water availability isaffected by rainfall and evapotranspiration which is a function of temperature,while the water demand is influenced by land use and population. From the waterbalance calculation the water availability in 2030 is less than 2010, this was due tothe effect of increasing air temperature increases, because increase of evaporationrate. Water Aviability in the year 2010 amounted to 3358.4 million m3 / year,while the water demand for irrigation is 669 million m3 / year (20%), household,urban and industrial amounted to 87.2 million m3 / year (3%), and 2602.2 millionm3 / year (77%), can not be used. Water Aviability in 2030 decreased compared to2010 amounted to 2498.9 million m3 / year, for irrigation amounted to 1133.7million m3 / year (45%), household, urban and industrial at 136.5 million m3 / year(4%), and 1228.8 million m3 / year (51%) con not be used. By 2010 the water wasstill meet the demand while by 2030, there will be a deficit in the month ofAugust and September, so that is the necessary support from reservoirs to storewater surplus, which will be used during the defisit period.;Climate change is a global issue that is currently being faced by the globalcomunity, which is strongly influenced by precipitation and air temperaturevariability. The research examines the increase rainfall and air temperature, duringthe period 1910-2010 in the Nasal-Padang Guci River Area, and its influences onwater balance. The study uses Mann Kendall Test to determine the trend line ofprecipitation and air temperature, The methode used water surplus and defisit toanalyze water balance. The temperature rise of 0,80 C/54 years on the average.Rainfall in the year 1910-1978 increase by 20 mm/69 years, this is consideredreasonable, and does not have any significant effect. However increasessignificantly in the year 1979-2010 it amounted to 125 mm/30 years. The increaseof precipitation and air temperature variability affects water availability and waterdemand, in the Nasal-Padang Guci river area, in this case water availability isaffected by rainfall and evapotranspiration which is a function of temperature,while the water demand is influenced by land use and population. From the waterbalance calculation the water availability in 2030 is less than 2010, this was due tothe effect of increasing air temperature increases, because increase of evaporationrate. Water Aviability in the year 2010 amounted to 3358.4 million m3 / year,while the water demand for irrigation is 669 million m3 / year (20%), household,urban and industrial amounted to 87.2 million m3 / year (3%), and 2602.2 millionm3 / year (77%), can not be used. Water Aviability in 2030 decreased compared to2010 amounted to 2498.9 million m3 / year, for irrigation amounted to 1133.7million m3 / year (45%), household, urban and industrial at 136.5 million m3 / year(4%), and 1228.8 million m3 / year (51%) con not be used. By 2010 the water wasstill meet the demand while by 2030, there will be a deficit in the month ofAugust and September, so that is the necessary support from reservoirs to storewater surplus, which will be used during the defisit period., Climate change is a global issue that is currently being faced by the globalcomunity, which is strongly influenced by precipitation and air temperaturevariability. The research examines the increase rainfall and air temperature, duringthe period 1910-2010 in the Nasal-Padang Guci River Area, and its influences onwater balance. The study uses Mann Kendall Test to determine the trend line ofprecipitation and air temperature, The methode used water surplus and defisit toanalyze water balance. The temperature rise of 0,80 C/54 years on the average.Rainfall in the year 1910-1978 increase by 20 mm/69 years, this is consideredreasonable, and does not have any significant effect. However increasessignificantly in the year 1979-2010 it amounted to 125 mm/30 years. The increaseof precipitation and air temperature variability affects water availability and waterdemand, in the Nasal-Padang Guci river area, in this case water availability isaffected by rainfall and evapotranspiration which is a function of temperature,while the water demand is influenced by land use and population. From the waterbalance calculation the water availability in 2030 is less than 2010, this was due tothe effect of increasing air temperature increases, because increase of evaporationrate. Water Aviability in the year 2010 amounted to 3358.4 million m3 / year,while the water demand for irrigation is 669 million m3 / year (20%), household,urban and industrial amounted to 87.2 million m3 / year (3%), and 2602.2 millionm3 / year (77%), can not be used. Water Aviability in 2030 decreased compared to2010 amounted to 2498.9 million m3 / year, for irrigation amounted to 1133.7million m3 / year (45%), household, urban and industrial at 136.5 million m3 / year(4%), and 1228.8 million m3 / year (51%) con not be used. By 2010 the water wasstill meet the demand while by 2030, there will be a deficit in the month ofAugust and September, so that is the necessary support from reservoirs to storewater surplus, which will be used during the defisit period.]