Karst springs Jadro, Žrnovnica and Pantana & karst river

Ognjen Bonacci Faculty of Civil Engineering, Architecture and Geodesy Split University 21000 Split, Matice hrvatske str. 15, E-mail: [email protected]

Geological map of the Jadro and Žrnovnica catchment

The catchment is composed mainly of carbonates, well permeable Mesozoic, Eocene and Perms limestone and less permeable dolomites and impermeable Triassic clastic deposits and Eocene flysch.

300 AC 2011 AC

The Jadro Spring is principal water -supply source for the Split town and wider surrounding area (> 300,000 inhabitants). Forming the river Jadro which inflow after the 4.5 km into the .

2011 AC 3 Qmean = 9.85 m /s (mean annual discharge) 3 (limited outflow capacity) Qmax = 70.1 m /s (18 Dec. 2004) 3 Qmin = 3.72 m /s (07 Aug. 1995)

ŽRNOVNICA SPRING 1990-2009

3 Qmean =1.83 m /s 3 Qmax = 16.7 m /s (18 Dec. 2004) 3 Qmin = 0.215 m /s (9, 10, 11, 14 Sep. 1993) Cetina River catchment Tracing experiments Konjsko

Catchment area and boundaries !!???

Bisko Polje Gizdavac Relationship between annual runoff (Q year ) and annual rainfall (P) on the catchment A

A

Qyear (m 3/s)

Q

Qyear = a + b P

b = y/x = tg α P 0 α y

x P (mm) 0

0 The regression line (Q year -P) crosses the abscissa at the point P0, which means that an annual rainfall equal to or smaller than a P0 could not cause any runoff on the catchment under consideration. The logical assessment is that water from the Cetina River catchment feeds the Jadro Spring.

P0 is between -376 and -663 mm ??? From the hydrological point of view this is unacceptable and can be explained by fact that the Jadro Spring is feed with water from another source. Time series of the mean annual discharges

measured

defined by Turc equation

2 2 D = P / 9.0 + P( / L ) 2 A JADRO-TURC = 502.5 km 3 2 L = 300 + 25 ×T + 05.0 ×T A ŽRNOVNICA-TURC = 80.1 km Relationship between the Jadro Spring mean annual discharges

defined by Turc equation (QTURC ) and measured data (QJADRO ) c – annual runoff coefficient

c - measured; cT - Turc

Subtraction of 6.01 m 3/s from the measured Jadro Spring mean annual discharges

P0 is between 515 and 620 mm 0,36 13,1

0,35 13

12,9 0,34 12,8 0,33 12,7

0,32 T (°C) 12,6 E. Vod. (mS/cm) 0,31 12,5

0,3 12,4

0,29 12,3 1 49 97 145 193 241 289 337 385 433 481 529 577 625 673 721 769 817 865 913 961 t (h)

t = 1h 28 Sep. – 8 Nov. 2010 (in progress…)

Tmin =12.38 ºC – Tmax =13.05 ºC

(1979-1985) T min =10.77 ºC – Tmax =15.02 ºC E.C. min =0.30 mS/cm - E.C. max =0.35 mS/cm 500-600 km 2 ?

Inner zone CONCLUSION ?

Outer zone

JADRO S. - ŽRNOVNICA S.

CETINA R. - JADRO S.

Analysis is in progress! Thank you for your kind attention!