Characterizing the climatic water balance dynamics and different runoff components in a poorly gauged tropical forested catchment, Nicaragua

Figures & data

Figure 1. Study catchment and selected sub-catchments. Black circles are groundwater level monitoring points for the period 2010–13 and rain gauge locations (1) Monteverde, (2) Montecristo and (3) Ostional. Grey circles are locations of soil infiltration tests. Topographic contour resolution is 100 m.

Table 1. Soil infiltration capacity.

Site	Infiltration capacity [mm h^-1]
1	50
2	48
3	40
4	45
5	36
6	13
7	18
8	36
9	15
10	10
11	10

Figure 2. Climatic water balance for the catchment for the period June 2010 to April 2013. (a) Monthly precipitation (P) for each station. (b) Reference evaporation (E_ref) at each station. (c) P–E_ref for the catchment based on areal weighted averages and average hydraulic head (h) fluctuations for wells at the three catchment communities.

Figure 3. Hysteresis in EC–discharge relationships during sub-catchment (a) and catchment (b and c) rainfall–runoff events. Hollow circles represent concentrations during the rising limbs, solid circles represent concentrations during the falling limbs, and arrows indicate time evolution.

Table 2. End-member composition for sub-catchment and catchment scale events.

Scale	End-member	SiO2 [mg L^-1]	Cl^- [mg L^-1]	δ^18O [‰]	δ^2H [‰]
Sub-catchment	Surface runoff	na	5.74	−7.40	−52.10
	Subsurface stormflow	na	16.11	−7.13	−40.80
	Groundwater	na	12.09	−6.34	−40.98
Catchment	Surface runoff	0.051	2.48	−7.45	−56.57
	Groundwater	0.748	18.91	−6.70	−43.30
	Baseflow	1.060	5.96	−6.27	−36.10

na: under the detection limit.

Table 3. Summary of rainfall-runoff events. Runoff coefficients are based on δ¹⁸O hydrograph separations.

Event	Scale	Area [km^2]	Date	Rainfall duration [h]	Max rainfall intensity [mm h^-1]	Rainfall amount [mm]	Peak discharge [m^3 s^-1]	Event runoff [mm]	Runoff coefficient [%]
1 (Rompeviento)	sub-catchment	0.8	15 August 2010	1.5	24.0	23.60	0.20	0.32	2.80
2 (Nancite)	sub-catchment	1.6	16 August 2010	2.4	22.8	25.20	1.00	2.57	12.98
3	catchment	46	19 October 2012	2.0	35.9	37.00	1.01	0.02	0.07
4	catchment	46	22 October 2012	4.0	40.5	30.72	0.59	0.02	0.12
5	catchment	46	25 October 2012	8.3	13.5	34.36	4.68	0.68	1.72

Figure 4. Hydrograph separation based on chloride and δ¹⁸O for events 1 and 2. Q_t: total discharge, Q_sr: surface runoff, Q_ssf: subsurface stormflow and Q_gw: groundwater.

Figure 5. Hydrograph separation based on δ¹⁸O and δ²H for events 1 and 2. Q_t: total discharge, Q_e: event water contribution and Q_p: pre-event water contribution.

Figure 6. Hydrograph separation based on chloride and δ¹⁸O for Events 3, 4 and 5. Q_t: total discharge, Q_sr: surface runoff, Q_b: baseflow and Q_gw: groundwater.

Figure 7. Hydrograph separation based δ¹⁸O and δ²H for Events 3, 4 and 5. Q_t: total discharge, Q_e: event water contribution and Q_p: pre-event water contribution.

Figure 8. Conceptualization of runoff generation at sub-catchment (a) and catchment scale (b).

Figure A1. Travertine deposits encountered during the dry season 2011 at the headwaters of the catchment.

Figure A2. Different landscape characteristics at sub-catchment (a) and catchment (b) level.

Figure A3. River baseflow during dry season 2012 in the upper catchment area.