KAJIAN NERACA AIR SECARA HIDROMETEOROLOGI DI KABUPATEN SLEMAN

UNIK OKTA FITRIANI, Ir. Supriyandono, M .Sc.

2007 | Skripsi | S1 KEHUTANAN

pAoilra s anhidguapt bmearhsyarakatubungan m eoradte dme nkgaurna nkge hmideungpahna rkagaire aniar tsiedbaakg aadi ab kareanhidgu vpiantal tsaenhpian gagira. kmeebreurpaadkaaann daaierr ahse dmeankgiann tjiudmaklah s peiemndbuandgu k dyeannggan cu kjuump ltainhg gpi,e ntedrumdausku. k Kdia bdalupaamtenny aS aledmalaahn Kunetcuakm mataenng eCtanahgkui rninegaracna, airKecam di Katanabu pPaatkeenm S, ledmana nK, ekchamusuastannya T durii K. Peceanmelaittianan Cinani gbekrrtiunjguanan, tKeresceabmuat.ta n Pakem, dan Kecamatan Turi serta untuk mengetahui indeks kekeringan di daerah Metode MTheotomdeth wyaanitge ddiagnu nMakaathne ru. nMtuekt omdeen inigh imtuenngg gnunakaneraca a iirn pdaluta dma tpae ynaenligti abne riunpi aa cdalurahah hduihjaitnu,n gsu haud,a lpahan jeanvagp opteranraksapriraans itan poatmenasni,a lda, n sifat fisik tanah. Beberapa parameter yang water holding capacity defisit air, serta (WHC), surplus dan run off data suhu udara rata-rata(a bliulananran per dmaunk fakaant)o. rE kvaorpeoktransi yanspigr asbeir pdasotearkannsial dbiulhiatnu ndga nm leentakgg ulinnatankang claerah penelitian. Nilai ST (storage) dihitung berdasarkan fungsi dari water holding capacity. Surplus dan defisit air dapat ditentukan setelah diketahui nilai storage. aliran permukaan yang terjadi adalah limapuluh persen dari s Prediksi urplus akan menjadi sedangkan limapuluh persen dari sisanya ditambahkan pada bulan berikutnya. Hasriul ndari off analisis neraca air diguHasil penelitianna kmane nuunntujukk mkaenn enbatuhkwana iKndeeckasm kaetanke riCngaanng krdaienrgahan temrseembuptu. nyai lima vTaurriia smi enmerpauncayai air ,ti gKae cvaamriaastani n Perakaceam a irnr.e Dmapeurnahya yi aenmgp mate varimpuansyai nie eravcapa oatriran, daspnir aKsie ctearmbaetasanr a1d.3a3lah4,7 K8 emcamm aptearn tCahaunng.k rWHingaCn pteardbae skairs adriajnu mhupjaain p 1a5d0a0 K-2e0c0a0m matanm pPear kteahmu nd,e nygaiatnu skeibsaersaanr curah hujan 3000-3500 mm per tahun, yaitu 200,08 mm. SurpKecamatan Cangkringan dengan kisaran curah hujan 3500-l4u0s 0t0er timngmg i pdeirte mtahukan pada un, 1.741,46 mm per tahun, sedangkan daerah yang paling besar mengalami defisit air adyaaliathu pKeerc atamhuatna. n Cangkringan dengan kisaran hujan 1500-2000 mm per tahun, yaitu 240,46 mm Run off hujan 3500-4000 mpamli npge br etahsar terjadi pada Kecamatan Cangkringan dengan kisaran curah un, mempunyai pengaruh terhadap kemayaimptuu anse mbeesnayri m1p3a0n6 amir mse rptae rd atlaahmu np.e nKgeebnedraaldiaana nd ahuur taanir dan run off. kekeringan kBaererdnaas parakdana s einmdueak sk kiseakraerni nhguajann,K deic kaemcaamtanat aPna kienmi b ererlaacltaif p laeclbiah in admeakns da0-1ri6 b, 7a h%ay

Water is closely related to the subsistence because nothing can live without water. Modem society's life style slight water as vital thing so it makes unbalancing between water and total inhabitans. Sleman Regency have hight total inhabitans, include Cangkringan District, Pakem District, and Turi District. The objective of the research is to know the water balance in Sleman Regency and the aridity index in that area. The method to account water balance in this research by Thomthwaite and Mather method. This method uses data of monthly rainfall, monthly average air temperature, the plant root length, and the soil physical characters. Some parameters counted are potential evapotranspiration, water holding capacity, water surplus and deficit, and run-off. Potential evapotranspiration was counted using monthly average air temperature and correction factor of moon and star position of the area. The storage scale was counted by the function of water holding capacity. Water surplus and deficit can be determined when the storage scale has been obtained. Run-off was gained from the surplus. Fifty percents surplus will become the run off while the rest fifty percents will be added to the next month storage. The result of water balance can be used to determine the aridity index in that area. The result of research shows that Cangkringan District have five water balance variations, Pakem District have four water balance variations, and Turi District have three water balance variations. The greatest potential evapotranspirarion obtained by Cangkringan District on the 1500-2000 mm per year range of rainfall as 1,334.78 mm per year. The biggest WHC obtained by Pakem District on the 3000-3500 mm per year range of rainfall as 200.08 mm. The greatest surplus founded at Cangkringan District on the 3500-4000 mm per year range of rainfall 1,741.46 mm per year, and then the biggest water deficit obtained by Cangkringan District Cangkringan District on the 1500-2000 mm per year range of rainfall as 240.46 mm per year. The greatest run off happened at Cangkringan District on the 3500-4000 mm per year range of rainfall, as 1,306 mm per year. Forest have great effects on the ability of water storage and also water cycle and run off control. Based on aridity index, Pakem District is more secure from the dry disaster than Cangkringan District and Pakem District because the aridity indeks in the range of 0- I 6. 7 %.

Kata Kunci : neraca air,evapotranspirasi,surplus,defisit,aliran permukaan,indeks kekeringan