Luni is the only river basin of any significance in Western Rajasthan, which form the bulk of arid zone. Luni originates from western slopes of the Aravalli ranges at an elevation of 772 m above m.s.l. near Ajmer flowing in South West direction and traversing a course of 511 km in Rajasthan, it finally flow into the Rann of Kachchh. Most of its tributaries drain the steep north west of Aravalli hills and join it on left side. Its total catchment area falls in Rajasthan. Luni basin is situated in between 24⁰ 11’ to 26⁰ 43’ North latitude and 70⁰ 37’ to 74⁰ 39’ East longitude approximately. The peculiarity of this river is that it tends to increase its width rather than deepening the bed because the banks are of soils, which are easily erodible whereas beds are of sand. The floods develop and disappear so rapidly that they have no time to scour the bed. The Aravalli ranges form its East boundary whereas main course of river in Barmer district itself forms North boundary and mostly Banas and initial reach of Chambal River form its Southern boundary.

Luni receive alol the main tributaries on its left bank except one i.e. Jojari (Mithri) on the right bank. Luni receives ten tributaries namely Lilari, Guhiya, Bandi (Hemawas), Sukri (Hemawas), Sukri, Mithri, Jawai, Khari Bani Sukri Bandi and Sugi. Hence the drainage on the left bank of Luni is, therefore, more extensive than on right bank. The Luni drains an area of 32879 sq.km. in Rajasthan state only.

The catchment area of the basin upto Chittalwana is 32661 sq.km. The remaining catchment area of the Luni basin below Chittalwana and upto Rann of Kachchh is only 218 sq.km. which is delta where the water spreads out and does not contribute any runoff. The total available runoff from entire Luni basin is 788 Mcum, out of which Guhiya, Jojari(Mithri), Bandi(Hemawas) and Jawai tributaries contribute runoff of 116 Mcum, 64 Mcum, 64 Mucm, 120 Mcum and 125 Mcum respectively. The catchment area, length and elevation of source of important tributaries are shown below:

The important irrigation schemes in Luni Basin are Jawai Dam, Jaswant Sagar dam, Hemawas, Sardar Samand. CWC is maintaining two H.O sites namely Gandhav (GD) and Balotra (GD)