Hatay-Erzin Ovası, Akdeniz bölgesinde, İskenderun körfezinin kuzeydoğusunda, Hatay ve Adana illeri sınırları içerisinde yer almaktadır. Ova alanı yaklaşık 300 $km^2$, drenaj alanı ise 350 $km^2$'dir. Çalışma alanının genel hidrojeolojik özelliklerinin yanısıra, boşalım sahasında yer alan ortalama 1.74 m3/s verime sahip Burnaz kaynağının beslenim-boşalım ilişkisi araştırılmıştır. Çalışma alanında akifer birimleri, İskenderun basenine ait Üst Pliyosen-Pléyistosen yaşlı Erzin formasyonunun çakıltaşı seviyeleri, Pliyokuvaterner - Kuvaterner yaşlı gözenekli bazalt ve Kuvaterner yaşlı alüvyonun kumlu, çakıllı seviyeleri oluşturmaktadır. Yeraltısuyu akım yönü kuzeydoğudan güneybatıya ve doğudan batıya (Akdeniz'e) doğrudur. Burnaz kaynağı, Pliyokuvaterner yaşlı bol gözenekli bazaltlardan, tektonik hatların kontrolünde alüvyonun geçirimsiz bölümleri boyunca birbirine oldukça yakın iki temel noktadan boşalan ve bu biçimi ile dokanak kaynağı olarak nitelendirilebilinen grup kaynağı özelliğindedir. Kaynak yıllık yağışların etkisi altında bulunan üçüncü tip akifer özelliğindeki bazalt akiferinden boşalmaktadır. Ovadaki su noktalarının birbirleriyle ve kaynak ile olan ilişkilerini hidrojeokimyasal açıdan araştırmak amacıyla sahadan alınan örneklerde su kimyası ve trityum analizleri yapılmıştır. Elde edilen sonuçlar, Burnaz kaynağının havza içindeki bazaltlardan yıllık yağışların etkisi ile beslendiğini, diğer su noktalarının ise akiferdeki derin dolaşım ve tuzlu formasyonlarla olan ilişkilere bağlı olarak kimyasal ve trityum içeriklerinde değişimler olduğunu göstermiştir.

Hatay-Erzin plain is located in northeast of Iskenderun gulf in the Mediterranean region. The area of plain is about 300 $km^2$ while its drainage area is 350 $km^2$. Along the Yumurtalık thrust, units of Miocene Misis-Andırın basin in north of study area has a tectonic contact with the units of Miocene Iskenderun basin at south. In addition to general hydrogeologic characteristics of the study area, discharge-recharge relation of the Burnaz spring in the discharge arek was also studied. Spring has a yield of 1.74 $m^3$/sec. On the basis of regular monthly discharge data of the spring in the years between 1976 and 1994, minimum and maximum flows are 0.947$m^3$/sec and 4.997$m^3$/sec, respectively. October and April average discharge values for a 19-year periodare 1.427$m^3$/sec and 2.206 $m^3$/sec, respectively. Plain is governed by Mediterranean climate regime. The annual average precipitation value recorded at Yeşilkent Observatory for the years 1967-1995 is 930.5 mm. There are a number of 200 wells (by 1995) in the area drilled by DSI in order to supply irrigation water for Erzin and Yeşilkent residential sites. Discharge measurements show that withdraw from these wells with increasing number does not affect the Burnaz spring. Well depths are about 150-200 m in upper parts (between 100-200 m) while 50-150 m in discharge area (between 50-50 m) at west. Conglomerate levels of upper Pliocene-Pleistocene Erzin formation of the iskenderun basin, Plio- Quaternary-Quaternary porous basalt and sandy and pebbly levels of Quaternary alluvium are the main aquifer units in the study area. On the basis of pumpage tests, transmissibility values are 105-6110$m^2$/day in conglomerate aquifer, 2708-14628 $m^2$/day in basalt aquifer and 987-5576 $m^2$/day in the whole aquifer. Flow direction of groundwater is from northeast to southwest and east to west (to the Mediterranean Sea). Hydraulic slope, which is high in the east, decreases to the west due to high permeability of basalt. In Erzin-Yeşilkent plain, groundwater recharge is 103.3 x 106 $m^3$/y, groundwater discharge is 128.8 x 106$m^3$/y and reserve exchange is $DeltaV=-25.5 x $10^6 m^3/y$. On the basis of groundwater level changes in the years between 1977 and 1996, regional draw in the recharge area is 4-20 m which fluctuates 1-3 m in the discharge area by the recharge of Burnaz spring. Recession coefficient $(alpha_{Ave})$ for the conglomerate aquifer is 1.52 x $10^{-3} day^{-1}$ which represents a tertiary type aquifer. Burnaz spring issues from two points through the Plio-Quaternary porous basalt along the impermeable parts of alluvium, thus it can be thought as a contact spring. Discharge elevation of the spring is about 5-6 m. On the basis of spring hydrographs obtained from monthly flow rates measured in the years between 1976-1994, annual average discharge, annual recharge of the spring and recession coefficient were calculated as 53.3 x $10^6 m^3/y$, 54.4 x $10^6 m^3/y$ and 4.21 x $10^{-3} day^{-1}$, respectively. In this respect, spring issues through the basalt aquifer which is greatly fed by annual precipitation. The correlation coefficient between annual average flow and annual rainfall is r=0.77. In order to examine hydrogeochemical relation between Burnaz spring and other water points in the plain, samples collected in the area were analyzed for major ion and tritium contents. Chemical and tritium results indicate that Burnaz spring issues through the basalts in its own recharge area and that it is a kind of contact spring. On the other hand, tritium contents of other water points located in the coastal areas changes by proportionally of the replenishment from the evaporitic formations.