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Home , Check dam, Groundwater recharge

Article The Impact of a Check on Recharge and in an Ephemeral

Hakan Djuma 1,* ID , Adriana Bruggeman 1, Corrado Camera 1,2, Marinos Eliades 1 and Konstantinos Kostarelos 3 1 , Environment and Water Research Centre, The Cyprus Institute, 2121 Aglantzia, Nicosia, Cyprus; [email protected] (A.B.); [email protected] (C.C.); [email protected] (M.E.) 2 Dipartimento di Scienze della Terra “A. Desio”, Università degli Studi di Milano, 20133 Milan, Italy 3 UH Energy Research Park, University of Houston, Houston, TX 77204-0945, USA; [email protected] * Correspondence: [email protected]; Tel.: +357-22-208607

Received: 18 September 2017; Accepted: 19 October 2017; Published: 24 October 2017

Abstract: Despite the widespread presence of check , there are few studies that quantify their functionality. The objectives of this study are (i) to assess groundwater recharge in an ephemeral with and without a and (ii) to assess build-up in the check-dam . Field campaigns were carried out to measure water flow, water depth, and check-dam topography to establish water volume, , outflow, and recharge relations, as well as sediment build-up. To quantify the groundwater recharge, a water-balance approach was applied at two locations: at the check dam reservoir area and at an 11 km long natural stretch of the river upstream. Prediction intervals were computed to assess the uncertainties of the results. During the four years of operation, the check dam (storage capacity of 25,000 m3) recharged the with an average of 3.1 million m3 of the 10.4 million m3 year−1 of streamflow (30%). The lower and upper uncertainty limits of the check dam recharge were 0.1 and 9.6 million m3 year−1, respectively. Recharge from the upstream stretch was 1.5 million m3 year−1. These results indicate that check dams are valuable structures for increasing groundwater in semi-arid regions.

Keywords: water balance model; measurement; sedimentation; infiltration; managed aquifer recharge; estimation errors; Cyprus; Mediterranean Island

1. Introduction Groundwater is an important source of water supply in semi-arid regions because it is protected from high evaporation rates that affect bodies. The of groundwater bodies is therefore very important, and induced groundwater recharge is one of the main methods for increasing the sustainable yield of a groundwater body [1–3]. Especially under change conditions, managed aquifer recharge systems could be more effective than increasing surface reservoir capacities [4] and could also be the most economically and socially feasible solution for the integrated management of [5]. A recharge check dam is a barrier that is placed across a river or to slow the movement of water, encouraging groundwater recharge. Several authors studied the groundwater recharge efficiency of check dams. Martin-Rosales et al. [6] quantified recharge by estimating the infiltration capacity of the reservoir bed of existing check dams by infiltrometer tests in south-eastern Spain. Infiltrometer tests could also be performed to test the infiltration of different geological units [7]. Alderwish [8] quantified groundwater recharge from three projected check dams in Yemen. The author compared a simple water balance model based on average measured saturated with a two dimensional recharge expression, based on Darcy’s law. He found that the total calculated recharge

Water 2017, 9, 813; doi:10.3390/w9100813 www.mdpi.com/journal/water Water 2017, 9, 813 2 of 16 rate over a 20 year period (2007 to 2026) using the Darcian approach was close to that calculated by the water balance method. He concluded that a simple water balance approach can provide acceptable results for the estimation of induced recharge when the scarcity of site-specific data limits the use of sophisticated analysis techniques. Racz et al. [9] found great spatial and temporal variations in pond infiltration rates, even in a single aquifer recharge reservoir. They noted that locations with the most rapid infiltration shifted laterally during the aquifer recharge event. However, few water balance studies at a single check dam with field data have been presented in the literature [9,10], and none presented associated uncertainties of their estimates. Recharge behind the check dam is affected not only by its location [11] but also by the build-up of sediment in its reservoir. This sediment build-up is a result of riverbank or erosion in the upstream watershed area, which is affected by use, climate, topography, and [12–18]. Sediment build-up and infiltration at check dams are generally studied separately, although the former can increase the uncertainty in the estimates of the latter, especially for water balance calculations. The objectives of this study were (i) to assess groundwater recharge in an ephemeral river with and without check dam and (ii) to assess the average annual sedimentation rate at the check dam during a four year period (2011 to 2015). The study was conducted on a check dam in the semi-arid island of Cyprus. Field campaigns were carried out to measure water flow, water depth, and check dam topography in order to establish check dam water volume, evaporation, outflow, and recharge relations. A water balance model was developed according to these relations and applied at two locations for the quantification of the groundwater recharge. The first location is at the check dam reservoir, while the second is along a natural stretch of river bed upstream of the check dam reservoir. Uncertainties of the estimates are reported in the form of prediction intervals.

2. Materials and Methods

2.1. Study Area This study was conducted in the Peristerona Watershed in Cyprus. The Peristerona River has an ephemeral water flow and is located on the north-eastern hill slope of the Troodos Mountains (Figure1). In its upstream part, the elevation ranges between 1540 and 900 m, with a mean local slope higher than 40% and a mean average (1980 to 2010) of 750 mm [19]. The geology of this area is dominated by intrusive rocks (sheeted dykes-Diabase), with smaller areas of cumulate rocks (gabbro and plagiogranites), of the Troodos ophiolitic sequence [20,21]. Upstream, the land is covered mostly with sclerophylous and mountain agriculture on terraces retained by dry-stone walls. Many of these terraces are abandoned with collapsed walls, and options for rehabilitation are being investigated [22]. The midstream area ranges between 900 and 500 m above sea level (a.s.l.). The geological formations consist of intrusive rocks of the basal group (over 50% dykes with screens of pillow lavas) and are mainly covered by pine forests, with an annual precipitation of 405 mm. The foothills of the Troodos Mountains are formed by pillow lavas (olivine, pyroxene, and phyric lavas) and outcrops of sedimentary formations (hydrothermal and deep water : umbers, shales, and mudstones) with occasional pockets of highly saline groundwater. The elevation ranges between 500 to 300 m a.s.l., with mean local slope of 20% and 360 mm annual precipitation. Within the downstream Mesaoria plain, the watershed narrows, and the mean local slope is lower than 8%, with an average precipitation of 270 mm. The geology mainly consists of sedimentary formations (mostly alluvium-colluvium: sands, silts, clays, and gravel) from the Pleistocene and the Holocene, which form a shallow unconfined groundwater system in connection with the riverbed [23]. The Peristerona River recharges the alluvium and the sedimentary Central and Western Mesaoria Aquifer (Figure1), which is the largest and most important groundwater reservoir in Cyprus [24]. Karydas et al. [25], who applied the empirical erosion model G2 to the Republic of Cyprus, found loss rates exceeding 20 tons hectare−1 in the Peristerona watershed. Water 2017, 9, 813 3 of 16 Water 2017, 9, 813 3 of 16

Figure 1. Location of the Peristerona Watershed and the Central and Western Mesaoria [26] Figure 1. Location of the Peristerona Watershed and the Central and Western Mesaoria Aquifers [26] in Cyprus and its geology with the transient and check dam zones magnified and the streamflow in Cyprusmeasurement and its locations geology marked with the (modified transient from and the check Digital dam Elevation zones Model magnified and Geological and the Map streamflow of measurementCyprus, Cyprus locations Geological marked Survey (modified Department). from the Digital Elevation Model and Geological Map of Cyprus, Cyprus Geological Survey Department). The study transect can be divided into two zones (Figure 1): the transient zone and the check Thedam studyzone. The transect transient can zone be divided is where into water two flow zoness without (Figure ponding,1): the while transient the check zone dam and zone the is check where the inflowing water flow ponds and flows out of the check dam reservoir. Seven groundwater dam zone. The transient zone is where water flows without ponding, while the check dam zone is recharge check dams have been constructed along the Peristerona River on sedimentary formations where the inflowing water flow ponds and flows out of the check dam reservoir. Seven groundwater in the Mesaoria plain. The most upstream check dam (named Orounda check dam) was selected for rechargethis checkresearch dams (Figure have 1). been This constructed structure was along completed the Peristerona in October River 2011, on while sedimentary the other formationssix were in the Mesaoriaconstructed plain. between The most1980 and upstream 1990 (not check shown). dam (named Orounda check dam) was selected for this research (Figure1). This structure was completed in October 2011, while the other six were constructed between2.1.1. 1980 Transient and 1990Zone (not shown). The river segment from Panagia Bridge (PB) to Orounda Bridge (OB) is 11 km long and is 2.1.1.referred Transient to as Zone the transient zone in this study (Figure 1). The geology of the transient zone can be Thedivided river into segment two sections: from Panagiathe first section Bridge is (PB)located to Oroundabetween PB Bridge and Alluvial (OB) is Start 11 km (AS), long with and a length is referred to asof the 7.8 transient km, and zoneits bedrock in this is studycomposed (Figure of intrusive1). The geologyand volcanic of the rocks. transient The second zone section can be is divided located into between AS and OB, with a length of 3.2 km, and its bedrock consists of alluvium and colluvium. The two sections: the first section is located between PB and Alluvial Start (AS), with a length of 7.8 km, watershed area up to PB is 77 km2, up to AS 98 km2, and up to OB 105 km2. and its bedrock is composed of intrusive and volcanic rocks. The second section is located between AS and OB, with a length of 3.2 km, and its bedrock consists of alluvium and colluvium. The watershed area up to PB is 77 km2, up to AS 98 km2, and up to OB 105 km2. Water 2017, 9, 813 4 of 16

2.1.2. CheckWater 2017 Dam, 9, 813 Zone 4 of 16 Orounda Bridge (OB) is the entrance of the check dam zone, and the Orounda check dam spillway 2.1.2. Check Dam Zone (OC) is the exit. This structure is made of . The check dam, with its reservoir (a) and a cross-sectionOrounda of the checkBridge dam (OB) (b),is the is presentedentrance of in the Figure check2 .dam The zone, check and dam the wall Orounda has five check concrete dam pipes spillway (OC) is the exit. This structure is made of gabions. The check dam, with its reservoir (a) and with 0.5a mcross-section diameters. of Thethe check elevation dam (b), of is the presented inlet of in the Figure pipes 2. variesThe check up dam to 10 wall cm, has and five the concrete slope ranges betweenpipes−0.6% with and0.5 m 0.3%. diameters. The spillwayThe elevation is constructed of the inlet of on the top pipes of varies the pipes up to and10 cm, is 30and m the long slope (the pipe spacingranges is about between 6 m), −0.6% 9.5 m and wide, 0.3%. and The 1spillway m high. is Theconstructed check damon top is of constructed the pipes and on is 30 an m alluvial long (the riverbed, characterizedpipe spacing by coarse is about gravel, 6 m), 9.5 cobbles, m wide, and and few 1 m boulders. high. The check A nearby dam is profile constructed borehole on an (see alluvial Figure 1 for location)riverbed, shows characterized that the aquifer by coarse consist gravel, of boulderscobbles, and and few gravel boulders. to a A depth nearby of profile 6 m, siltyborehole sand (see with fine Figure 1 for location) shows that the aquifer consist of boulders and gravel to a depth of 6 m, silty gravel from 6 to 18 m, fine gravel with sandy marl from 18 to 21 m, sand from 21 to 52 m, and marl sand with fine gravel from 6 to 18 m, fine gravel with sandy marl from 18 to 21 m, sand from 21 to 52 from 51m, to and 334 marl m (Cyprus from 51 to Geological 334 m (Cypru Surveys Geological Department). Survey Department).

FigureFigure 2. Orounda 2. Orounda check check dam damwith with ( aa)) its its reservoir reservoir and and (b) its (b )cross-section. its cross-section.

2.2. Field2.2. Monitoring Field Monitoring The Water Development Department of Cyprus has measured streamflow continuously at PB Thewith Water a Development since 1960. In Department addition to the of co Cyprusntinuous has measurements, measured streamflow instantaneous continuously streamflow at PB with ameasurements weir since 1960. were Inmade addition twice per to theweek. continuous The streamflow measurements, velocity was instantaneous measured with streamflow an measurementselectromagnetic were flowmeter made twice (OTT MF per pro; week. Kempten, The Germany) streamflow at 0.6 of velocity the depth was and measuredmultiplied by with an electromagneticthe cross-sectional flowmeter area of (OTT the stream MF pro; water Kempten, profile to Germany)obtain discharge at 0.6 (m of3 s− the1) using depth the andmid-section multiplied by the cross-sectionalmethod [27]. The area distances of the stream between water the stations profile (verti to obtaincal sections) discharge in each (m profile3 s−1 were) using such the that mid-section no individual station contains more than 10% of the total discharge. The maximum observed methodstreamwater [27]. The distancesprofile was between 0.7 m deep the and stations 11 m wide. (vertical Measurements sections) were in each made profile during werethe 2014 such to that no individual2015 station streamflow contains season more (December than 10%2014 ofto theJune total 2015) discharge. at two locations The maximum(AS and OB). observed Between these streamwater profile waspoints, 0.7 two m deepirrigation and channels, 11 m wide. one on Measurements the east and were one made on the during west bank, the 2014divert tosome 2015 of streamflowthe season (Decemberstream water 2014 to the to downstream June 2015) atagricultural two locations fields. (AS Twice and weekly OB). Betweenmeasurements these of points, flow in two these channels,channels one onwere the made east to bank estimate and the one amount on the of westwater bank,diverted. divert Diversions some to of the the irrigation stream water to the were irregular. Also, sometimes water was released back to the streambed downstream from the downstream agricultural fields. Twice weekly measurements of flow in these channels were made inlets and before OB. to estimate the amount of water diverted. Diversions to the irrigation canals were irregular. Also, sometimes water was released back to the streambed downstream from the canal inlets and before OB. For the check dam zone, flow measurements were made at OB and OC (Figure1) approximately twice per week during 2014 to 2015. In addition, the groundwater levels in two wells were measured approximately twice per week. The well locations are presented in Figure1. Detailed topographic Water 2017Water, 9 2017, 813, 9, 813 5 of 165 of 16

For the check dam zone, flow measurements were made at OB and OC (Figure 1) approximately mappingtwice (scale per week of 1:1000) during of2014 the to check2015. In dam addition, area wasthe groundwater made, when levels the riverin two had wells no were water measured in Summer approximately twice per week. The well locations are presented in Figure 1. Detailed topographic 2013. Differential Global Positioning System (DGPS) and a total station (Leica, Heerbrugg, Switzerland) mapping (scale of 1:1000) of the check dam area was made, when the river had no water in Summer were employed. A Triangular Irregular Network (TIN) model was created from the acquired points 2013. Differential Global Positioning System (DGPS) and a total station (Leica, Heerbrugg, usingSwitzerland) ArcGIS (ESRI, were Redlands, employed. CA, A Triangular USA). With Irre knowngular Network dimensions, (TIN) relationsmodel was between created waterfrom the inflow, depthacquired of the water points in using the check ArcGIS dam (ESRI, reservoir Redlands, (h), and CA, open USA). water With surface known area dimensions, (A) were relations established. Thebetween volume water and inflow, mass depth of sediment of the water in the in the ponding check dam area reservoir were measured (h), and open in Summer water surface 2013 andarea 2015. The depth(A) were of theestablished. sediment layer was measured with utility poles. Bulk density samples (kg m−3) of the sedimentThe profilevolume wereand mass collected of sediment and averaged in the pondin to computeg area were the measured sediment in Summer mass from 2013 24 and locations. 2015. The depth of the sediment layer was measured with utility poles. Bulk density samples (kg m−3) of 2.3. Waterthe sediment Balance profile Computations were collected and averaged to compute the sediment mass from 24 locations.

For2.3. Water the transient Balance Computations zone, linear regression relations were derived to link the continuous flow measurements at PB to the instantaneous flow measurements at AS and OB. The obtained relations For the transient zone, linear regression relations were derived to link the continuous flow were then used to estimate the daily flow at AS and OB for the period from 2011/2012 to 2014/2015 measurements at PB to the instantaneous flow measurements at AS and OB. The obtained relations (hydrologicalwere then years).used to estimate Hydrological the daily yearsflow at are AS and considered OB for the from period 1st from September 2011/2012 toto 2014/2015 31th August. The difference(hydrological in theyears). total Hydrological flow between years the are two considered measurement from 1st points September was considered to 31th August. groundwater The rechargedifference (above in zero) the total or discharge flow between (below the zero).two me Anasurement estimate points of the was evaporation considered from groundwater the transient zone wasrecharge made (above with zero) Equation or discharge (2) presented (below below,zero). An using estimate data fromof the nearby evaporation stations from and the multiplying transient it with thezone surface was made area with of theEquation stream (2) water, presented estimated below, fromusing satellitedata from images. nearby stations and multiplying Toit with estimate the surface the groundwater area of the stream recharge water, from estimated the check from dam,satellite water images. balance calculations, the main componentsTo estimate of which the are groundwater presented recharge in Figure from3 and the Equationcheck dam, (1), water were balance made. calculations, The daily the check main dam components of which are presented in Figure 3 and Equation (1), were made. The daily check dam recharge was calculated as: recharge was calculated as: Qr = Qin − Qout − Qe + Vd − Vd−1 (1) = − − + − (1) where Qr is the recharge from the reservoir area, Qin is the water inflow, Qout is the water outflow, Qe is where Qr is the recharge from the reservoir area, Qin is the water inflow, Qout is the water outflow, Qe the evaporation, and Vd and Vd−1 are the volumes of water stored in the check dam reservoir area on is the evaporation, and Vd and Vd−1 are the volumes of water stored in the check dam reservoir area the and previous day, respectively. All units are in m3. on the current and previous day, respectively. All units are in m3.

FigureFigure 3. 3.Check Check dam dam waterwater balance components. components.

The inflow (Qin) was estimated with a linear regression model. Evaporation was calculated using Thean equation inflow (thatQin )is was a combination estimated of with the amass-transfer linear regression equation model. introduced Evaporation by Harbeck was [28] calculated (suitable using an equationfor lakes that with is a a surface combination area (A) of in the the mass-transfer range of 50 m equation< A0.5 < 100 introduced km located byin arid Harbeck environments) [28] (suitable for lakesand withthe equation a surface of Penman area (A) and in Priest the rangeley-Taylor of 50 modified m < A0.5 by< de 100 Bruin km [29]: located in arid environments) and the equation of Penman and Priestley-Taylor modified by de Bruin [29]: = ()( −) (2) −1 ∆+  α  γ  where A is the area of surfaceQ watere = (m2), γ is the psychometricf (u)( ecoefficients − e)A (-), es is the mean saturation (2) α − 1 ∆ + γ vapour of the air (kPa), e is the actual vapour pressure of the air (kPa), Δ is the slope of the 0−1 vapour pressure curve (kPa C ), and2 α is the Priestley-Taylor coefficient defined as: where A is the area of surface water (m ), γ is the psychometric coefficient (-), es is the mean saturation vapour pressure of the air (kPa), e is the actual vapour pressure of the air (kPa), ∆ is the slope of the vapour pressure curve (kPa C0−1), and α is the Priestley-Taylor coefficient defined as:

1 + γ  ∝= ∆ (3) (1 + β) Water 2017, 9, 813 6 of 16 where unitless β is the ratio of sensible to latent heat flux with a default value of 0.6 [30]. The value of the function of wind speed (f (u)) is derived from the mass-transfer equation introduced by Harbeck [28]:

f (u) = 2.909A−0.05u (4) where u is a wind speed 2 m above ground (m s−1). Daily meteorological data is obtained from nearby stations. Actual measurements of flow at OB and OC and measurements of h (the water height in the check dam) were used to relate, through regression models, h to Vd(h), Qout(h), and Qr(h). To derive Qr(h), water balance calculations were performed only with actual measurements. The derived functions were used to calculate the daily potential Qout and Qr, which set the daily upper limits. However, the actual Qout and Qr values can be lower than the estimated Qout(h) and Qr(h) because the rate of the change in h throughout a day is ignored. In order to average this change and reduce the error in the estimates, the h value in the middle of a day (hmid) is taken for the calculations; hmid is the h of the total water at the end of the previous day in the reservoir plus half of the Qin of the current day. Summarizing, daily Qr and Qout were calculated as:     Qin Qr = min Qr(h ), V − + − Qe(h ) (5) mid d 1 2 mid

(  min Qout(hmid), Vd−1 + Qin − Qr − Qe(hmid) − Vp1 for Vd > Vp1 Qout = (6) 0 for Vd ≤ Vp1 where Qe(hmid) is the volume of water evaporated from an open water reservoir area given a water 3 height hmid, and Vp1 is the volume of the water (m ) up to the bottom of the pipes. Considering the amount of annual rainfall and the dimensions of the check dam and the spillway, it is assumed that when the water level reaches an elevation above the spillway bottom, all overflow is exhausted in a single day. Therefore, for Vd, Qe, and Qr calculations, h is limited up to the spillway bottom elevation. The calculations were performed with Microsoft Excel® (Redmond, WA, USA).

2.4. Uncertainty Analyses Uncertainty is presented by calculating the 90% prediction intervals of the estimated values [31]. These prediction intervals are referred to as uncertainty intervals and are expected to cover measurement errors. Errors in the discharge measurement with an electromagnetic flowmeter are computed as ±6%. This value is the average calculated from six stations (single depth acquisition) with a declared accuracy of the OTT flowmeter of 2% [27,32]. All measured streamflow values were less than 6 m3 s−1. In the literature, comparable error values have been reported for similar measurement ranges [33]. For the weir measurements, errors are also assumed to be ±6% [34]. The uncertainty intervals of the evaporation estimates were considered ±5%, based on literature [35]. The upper and lower bounds of the uncertainty intervals were calculated both for the transient flow and the check dam zone. In addition to the model results with the best estimates (BE) of the components, the water balance was recalculated with the upper and lower bound uncertainty interval values of each component. The aim was to obtain maximum recharge (Qr_max) and minimum recharge (Qr_min) estimates as follows:

Qr_max = Qin_max − Qout_min − Qe_min + Vd − Vd+1 (7)

Qr_min = Qin_min − Qout_max − Qe_max + Vd − Vd+1 (8) where Qr_min, Qin_min, Qout_min, and Qe_min are the lower bounds and Qr_max, Qin_max, Qout_max, and Qe_max are the upper bounds of the uncertainty intervals. Negative lower bounds were set to zero. Water 2017, 9, 813 7 of 16

3. ResultsWater 2017 and, 9, 813 Discussion 7 of 16

3.1. Transient3. Results Zone and Discussion

3.1.Figure Transient4 shows Zone the linear regression fits of the observed flow discharge (2014 to 2015) at PB with AS (Figure4a) and OB (Figure4b). The linear relation models produced reliable results because Figure 4 shows the linear regression fits of the observed flow discharge (2014 to 2015) at PB with the watershed area between PB and OB is relatively small compared with the total watershed area AS (Figure 4a) and OB (Figure 4b). The linear relation models produced reliable results because the (27%watershed of the total area watershed between PB area) and andOB is no relatively secondary small compared with with continuous the total watershed flow contribute area (27% to the riverof in the between total watershed these points. area) and Another no secondary reason stream for thes calculatedwith continuous good flow fit is contribute that the watershedto the river area upstreamin between of PB receivesthese points. most Another of the precipitationreason for the (area-averaged calculated good precipitation fit is that the is 1.7watershed times more area than the precipitationupstream of PB between receives ASmost and of the OB) precipitation and would (area-averaged be expected precipitation to produce is more 1.7 times runoff, more as than it is the mountainousthe precipitation region ofbetween the watershed. AS and OB) As and expected, would be the expected uncertainties to produce for the more PB-AS runoff, stretch as it areis the slightly lowermountainous than those region for the of longerthe watershe PB-OBd. As stretch. expected, Any the computed uncertainties negative for the PB-AS values stretch were are assumed slightly to be zero.lower The modelled than those flow for the at ASlonger and PB-OB OB was stretch. considered Any computed to be zero negative for the values days whenwere assumed the measured to be flow zero. The modelled flow at AS and OB was considered to be zero for the days when the measured at PB was zero. Our field observations supported this assumption. flow at PB was zero. Our field observations supported this assumption.

Figure 4. Linear regression of the observed flow data at Panagia Bridge weir (PB) with (a) Alluvial Figure 4. Linear regression of the observed flow data at Panagia Bridge weir (PB) with (a) Alluvial Start (AS) and (b) Orounda Bridge (OB), with 90% prediction intervals. Start (AS) and (b) Orounda Bridge (OB), with 90% prediction intervals.

BasedBased on theseon these linear linear models, models, the the flow flow atat PBPB needsneeds to to exceed exceed 0.10 0.10 m m3 s3−1 sto−1 beto hydraulically be hydraulically connectedconnected to AS to andAS and 0.23 0.23 m3 ms3− s1−1to to bebe connectedconnected to to OB. OB. This This was was expected expected since since the distance the distance between between PB andPB and OB OB is longeris longer than than thatthat between PB PB and and AS. AS. In addition, In addition, when whenthe discharge the discharge at PB is less at PBthan is less 3 −1 than2.5 2.5 m m3 ss−, 1the, the discharge discharge at atAS AS is islower lower than than PB, PB, indicating indicating transmission transmission losses losses from fromthe stream the stream (groundwater recharge) along the PB-AS river stretch. When the discharge at PB exceeds 2.5 m3 s−1, (groundwater recharge) along the PB-AS river stretch. When the discharge at PB exceeds 2.5 m3 s−1, the discharge at AS is greater than that at PB, indicating river discharge gains from groundwater or the discharge at AS is greater than that at PB, indicating river discharge gains from groundwater small side streams. Similarly, for the AS-OB river stretch, the threshold between transmission losses or smalland gains side streams.can be set Similarly,for a discharge for theat AS AS-OB of 1.2 m river3 s−1. stretch,The Cyprus the Geological threshold Survey between Department transmission 3 −1 lossesmeasures and gains groundwater can be set levels for approximately a discharge atonce AS per of month 1.2 m ins wells. The in the Cyprus proximity Geological of the river Survey Departmentbed. The measuresgroundwater groundwater surface elevation levels in approximatelythese wells from once2011 perto 2015 month was innever wells higher in the than proximity the of thestreambed river bed. elevation The groundwater during the streamflow surface elevation season, suggesting in these wellsthat the from increase 2011 toin 2015streamflow was never higherdownstream than the streambedof AS is most elevation likely caused during by the side streamflow streams. Similar season, streamflow suggesting behavior that the has increase been in streamflowreported downstream in the literature of for AS is most in arid likely and caused semi-arid by , side streams. e.g., [36–38]. Similar Barthel streamflow and Banzhaf behavior has been[38] noted reported the difficulties in the literature of modelling for rivers such insurface arid water and semi-arid and groundwater climates, interactions e.g., [36– 38because]. Barthel the and parameters tend to exhibit large spatial and temporal variabilities. Banzhaf [38] noted the difficulties of modelling such surface water and groundwater interactions because the parameters tend to exhibit large spatial and temporal variabilities.

Water 2017, 9, 813 8 of 16 Water 2017, 9, 813 8 of 16

3.2. Check3.2. DamCheck ZoneDam Zone FigureFigure5a presents 5a presents the relationsthe relations between between checkcheck dam dam storage storage volume, volume, open open water water surface surface area, area, and water height, and Figure 5b presents the TIN model of the check dam topography created with and water height, and Figure5b presents the TIN model of the check dam topography created with the data collected in Summer 2013. The volume of the check dam storage up to the bottom of the the datapipes collected (261.07 in m Summer a.s.l.) was 2013. calculated The volumeas 14,216 of m the3, and check up to dam the spillway storage upbottom to the (262 bottom m a.s.l.) of as the pipes 3 3 (261.0724,923 m a.s.l.) m3. was calculated as 14,216 m , and up to the spillway bottom (262 m a.s.l.) as 24,923 m .

FigureFigure 5. (a) 5. Check (a) Check dam dam storage storage volume volume (primary (primary y-axis)y-axis) and andopen openwater watersurface surfacearea (secondary area (secondary y- y-axis)axis) changes changes with with water water height; height; ( b(b)) TINTIN of of the the check check dam dam created created with with topographic topographic data collected data collected in in Summer 2013. Summer 2013.

Figure 6a,b presents, respectively, the Qr values obtained by water balance calculations with Figureobserved6a,b data presents, and their respectively, exponential relation the Q tor values h and the obtained observedby values water of Q balanceout and h and calculations a third with order polynomial trendline, which was used for modelling the potential daily Qout (h) up to the observed data and their exponential relation to h and the observed values of Qout and h and a third spillway bottom. The upper and lower limit lines of the 90% prediction interval are also presented. order polynomial trendline, which was used for modelling the potential daily Qout(h) up to the spillway The derived exponential Qr-h relation is supported by the exponential increase of the water bottom.volume The upper in the andcheck lower dam reservoir limit lines with of increasing the 90% h prediction (Figure 5a). interval This equation are also was presented. used to model Thethederived potential exponentialQr (h). It can be Qseenr-h fromrelation the Qr is-h supportedobservations bythat theQr increases exponential slowly increasewith increasing of the water volumeh inand the then check (around dam h equal reservoir to 3.8 withm) increases increasing abruptly.h (Figure This can5a). be Thiscaused equation by the fact was that used the bottom to model the potentialof theQr (checkh). It dam can bereservoir seen fromis below the theQ rground-h observations level of the thatsurroundingsQr increases and the slowly lower withpart of increasing the h and thenreservoir (around wallsh equalare thicker to 3.8 than m) the increases upper parts abruptly. and partly This covered can be with caused sediment. by the The fact upper that parts the bottom of the reservoir walls are above ground level, built with boulders and without sediment cover. of the check dam reservoir is below the ground level of the surroundings and the lower part of the Therefore, Qr can occur slowly to a certain level of h and then increase rapidly. However, instead of reservoirhaving walls two are Q thickerr-h relations than (one the for upper smaller parts and andone for partly higher covered values withthan the sediment. threshold The h), a upper single parts of the reservoirexponential walls relation are above was groundassumed. level, The single built expo withnential boulders relation and has without the advantage sediment of reflecting, cover. Therefore, Qr canbetter occur than slowly two todistinct a certain linear level relations, of h thande expected then increase uncertainties rapidly. associated However, with the instead Qr estimates, of having two as the upper and lower limits of the prediction interval show a relatively wide possible range of Qr Qr-h relations (one for smaller and one for higher values than the threshold h), a single exponential relationvalues was given assumed. a certain The h. High single uncertainties exponential are expected relation because has the of three advantage main reasons: of reflecting, (i) the hourly better than change in Qr is expected to play a role and daily measurements alone are not able to reflect this; (ii) two distinct linear relations, the expected uncertainties associated with the Qr estimates, as the upper Qr is calculated from measured water balance components, which means that the measurement errors and lowerof each limits component of the contribute prediction to intervalthe error in show Qr estimates; a relatively and (iii) wide sediment possible build-up range in the of Qreservoirr values given a certaincanh cause. High changes uncertainties in Qr over time. are expectedFrequent measurements because of of three the flows main and reasons: sediment-build (i) the up hourly could change in Qr isimprove expected the Q tor estimates. play a role and daily measurements alone are not able to reflect this; (ii) Qr is calculated from measured water balance components, which means that the measurement errors of each component contribute to the error in Qr estimates; and (iii) sediment build-up in the reservoir can cause changes in Qr over time. Frequent measurements of the flows and sediment-build up could improve the Qr estimates. Water 2017, 9, 813 9 of 16

Water 2017, 9, 813 9 of 16

Figure6Figureb shows 6b that,shows although that, although the observed the observed pipe pipe discharge discharge ( Q out(Qout) is) is affected affected by by differences differences among the bottomamong heights the bottom and heights slopes and of theslopes pipes of the and pipes by and disturbances by disturbances at the at the inlet inlet of of the the pipes, pipes, the Qout-h polynomialQout-hrelation polynomial is similarrelation is to similar the typical to the typical water wate depthr depth to discharge to discharge relation relation for for circular pipes. pipes.

Figure 6. (a) Groundwater recharge (Qr) values (derived from water balance calculations with observed Figure 6. (a) Groundwater recharge (Qr) values (derived from water balance calculations with data) and (b) observed check dam outflow (Q ) with reservoir water depth (h) and best-fit trend lines observed data) and (b) observed check damout outflow (Qout) with reservoir water depth (h) and best-fit with uppertrend and lines lower with upper limit and of90% lower prediction limit of 90% interval. prediction interval.

3.3. Water3.3. BalanceWater Balance Components Components Table 1 shows the total annual water balance components of the transient and the check dam Table1 shows the total annual water balance components of the transient and the check dam zones. zones. From the 11 km long transient zone, a total of 5.96 million m3 stream water is lost as 3 From thetransmission 11 km long losses transient or recharged zone, to athe total groundwater of 5.96 millionover four m years.stream Evaporation water is calculated lost as transmission to be losses or8% recharged of the total loss to the (not groundwater presented). For overthis zone, four the years. total losses Evaporation are 4.6 times is higher calculated for the to segment be 8% of the total lossbetween (not presented). PB and AS (7.8 For km this long zone, on fractured the total bedr lossesock) than are for 4.6 the times segment higher between for the AS segmentand OB (3.2 between PB andkm AS long (7.8 on km alluvial long deposits). on fractured This could bedrock) be due thanto three for main the reasons: segment (i) the between majority AS of the and flow OB is (3.2 km generated upstream of PB, and, because PB-AS and AS-OB are both segments with transmission long on alluvial deposits). This could be due to three main reasons: (i) the majority of the flow is losses, the downstream stretch (AS-OB) receives less flow for recharge (over the four year period, generatedthere upstream were 1029 days of PB, of flow and, at becausePB, 605 days PB-AS at AS, andand 401 AS-OB days at are OB); both (ii) the segments PB-AS segment with crosses transmission losses, thefour downstreamdifferent geological stretch units (AS-OB) (Figure 1), receives two of which less floware classified for recharge as high-groundwater-recharge (over the four year period, there wereunits 1029 due daysto their of fractured flow at PB, 605 [21], days so atprefer AS,ential and flow 401 dayspaths atpotentially OB); (ii) exist the PB-ASand transmission segment crosses four differentlosses and geological groundwater units recharge (Figure could1), be two higher of which than in are the classifiedalluvial deposits as high-groundwater-recharge [38,39]; and (iii) a faster units dueincrease to their of the fractured streamflow nature at AS-OB [21], compared so preferential with PB-AS. flow Several paths potentiallyfield observations exist support and transmission the third reason as the most important. The PB-AS segment is mostly covered with natural vegetation losses and groundwater recharge could be higher than in the alluvial deposits [38,39]; and (iii) a faster (e.g., coniferous ), which creates with relatively higher rainfall events in increasecomparison of the streamflow with the bare at land AS-OB for the compared segment AS-OB with PB-AS.[18]. In fact, Several opposite field to AS-OB, observations the streams support at the third reasonPB-AS as were the mostobserved important. to start flowing The PB-AS and dischargin segmentg is only mostly after coveredhigh rainfall with events. natural In vegetationaddition, (e.g., coniferousirrigation forest), diversions which createsalong AS-OB surface can runoffalso be withreasons relatively for a rapid higher increase rainfall of the eventsstreamflow. in comparison The with thecapacity bareland of the for irrigation the segment canals is AS-OB limited [and,18]. after In fact,large oppositeflows, their to inlet AS-OB, can be the blocked streams by the at PB-AS were observeddebris. The to starteffect flowingof the third and reason discharging can be obse onlyrved after when high we compare rainfall the events. model In estimates addition, of the irrigation streamflow of a wet and a dry year. During the wet 2011 to 2012 season, the model estimated a total diversions along AS-OB can also be reasons for a rapid increase of the streamflow. The capacity of the 0.7 million m3 increase in streamflow between AS and OB, while, during the dry 2012 to 2013 season, irrigationalong canals the same is limited stretch, and, the model after largeestimated flows, a total their of 1 inlet million can m be3 in blocked transmission by the losses. debris. The effect of the third reason can be observed when we compare the model estimates of the streamflow of a wet and a dry year. During the wet 2011 to 2012 season, the model estimated a total 0.7 million m3 increase in streamflow between AS and OB, while, during the dry 2012 to 2013 season, along the same stretch, the model estimated a total of 1 million m3 in transmission losses. Water 2017, 9, 813 10 of 16

Table 1. Observed flows at Panagia Bridge (PB) and modelled flows at Alluvial Start (AS) and Orounda Bridge (OB), constituting the water balance components of the

transient and check-dam zone, where Qr is the recharge from the reservoir area, Qin is the water inflow, Qout is the water outflow, and Qe is the evaporation with the best estimate. The uncertainty intervals of the modelled results are presented.

Transient Zone Check Dam Zone Flow at PB Flow at OB = Qin Precip. a Flow at AS (Modelled) Qr Qe Qout Year (Observed) (Modelled) (106 m3) (106 m3) (106 m3) (106 m3) (106 m3) (106 m3) (106 m3) B b L-U b B L-U B L-U B L-U B L-U 2011–2012 75.56 23.99 23.13 19.56–28.74 23.84 20.24–30.43 5.86 0.26–13.04 0.007 0.014–0.014 17.98 17.38–19.96 2012–2013 52.38 8.61 7.22 4.46–12.65 6.25 3.97–12.62 2.93 0.04–8.56 0.004 0.014–0.013 3.31 4.05–3.92 2013–2014 37.95 1.63 0.41 0.01–6.26 0.04 0.00–6.90 0.04 0.00–6.87 0.001 0.004–0.017 0.00 0.01–0.00 2014–2015 65.54 13.39 11.95 8.99–18.09 11.54 8.91–18.74 3.62 0.07–10.14 0.004 0.008–0.013 7.91 8.57–8.83 Total 231.43 47.62 42.72 33.03–65.73 41.66 33.13–68.69 12.44 0.37–38.61 0.02 0.004–0.06 29.21 30.00–32.71 Notes: a Precipitation is calculated over the watershed area up to the check dam with area-weighted average, based on Thiessen polygons created with eight gauges. b B: Best estimate, L-U: Lower and Upper limit of the uncertainty interval. Water 2017, 9, 813 11 of 16 Water 2017, 9, 813 11 of 16

For the check dam zone, 30% of the total four year inflowinflow in thethe reservoirreservoir areaarea waswas transformedtransformed intointo groundwatergroundwater rechargerecharge (Table (Table1). 1). The The percentage percentage of of the the recharge recharge over over the the total total inflow inflow depends depends on theon the distribution distribution of the of inflow.the inflow. The totalThe amounttotal amou of groundwaternt of groundwater recharge recharge in 2011 in to 2011 2012 to was 2012 double was thedouble amount the amount in 2012 toin 2013.2012 to However, 2013. However, the percentage the percentage of the recharge of the recharge over the over total the inflow total for inflow 2011 for to 20122011 wasto 2012 25% was and 25% for 2012and for to 20132012 wasto 2013 47%. was 47%. Our best recharge estimate from the checkcheck damdam (30%(30% ofof thethe streamflow)streamflow) fallsfalls inin betweenbetween thethe ranges estimated by Martin-Rosales et al. [[7]7] for 67 check dams in semi-arid south-eastern Spain. TheseThese authorsauthors simulatedsimulated streamflowstreamflow withwith aa hydrologicalhydrological modelmodel andand extrapolatedextrapolated rechargerecharge volumesvolumes fromfrom infiltrometerinfiltrometer tests,tests, performedperformed onon aa permeable substrate similar to the one in our check dam dam area. area. TheThe checkcheck dam dam reservoir reservoir volumes volumes were were also also comparable: comparable: between between 12,000 12,000 and 34,000and 34,000 m3 for m their3 for study; their 25,000study; m25,0003 in our m3 research.in our research. They concluded They concluded that the that percentage the perc ofentage recharge of recharge over the over total the inflow total rangedinflow betweenranged between 6 and 53%, 6 and with 53%, higher with values higher for values higher for check-dam higher check-dam capacities. capacities. At the PanagiaPanagia Bridge weir station (PB) (Figure1 1),), surfacesurface runoffrunoff fromfrom thethe up- up- and and midstream midstream areas averaged 16% of the precipitation during the drier years and 32% during the wetter years [40]. [40]. Based on our model estimates, the average annual recharge from bothboth transient andand checkcheck dam zones equals 4.6 millionmillion mm33, whichwhich isis 38%38% ofof thethe observedobserved PBPB discharge.discharge. BasedBased onon groundwatergroundwater modelmodel calibrations for the Western Mesaoria,Mesaoria, UdluftUdluft etet al.al. [[41]41] foundfound that groundwater recharge from riversrivers − totalledtotalled 33.833.8 millionmillion mm33 yearyear−11. .Assuming Assuming that that approximately approximately one one th thirdird of of this amount is dischargeddischarged by thethe PeristeronaPeristerona River,River, based based on on its its watershed watershed size size relative relative to to the the other other rivers, rivers, this this number number seems seems to overestimateto overestimate recharge, recharge, considering considering that that the the mean mean annual annual discharge discharge (1980 (1980 to to 2010) 2010) ofof thethe PeristeronaPeristerona − River at the Panagia BridgeBridge weirweir stationstation (PB,(PB, FigureFigure1 1)) equals equals 9.75 9.75 million million m m33 year−11 [40].[40]. Figure7 7 shows shows groundwatergroundwater levelslevels inin WellsWells 11 andand 2, 2, the the water water level level in in the the check check dam, dam, and and the the precipitation and inflowinflow toto thethe reservoirreservoir areaarea overover time.time. NoNo groundwatergroundwater levellevel observationsobservations werewere made beforebefore JanuaryJanuary 2015. 2015. It It can can be be observed observed that that the the groundwater groundwater levels levels follow follow a similar a similar trend trend as the as waterthe water levels levels in the in check the check dam, dam, while while they dothey not do relate not relate to streamflow to streamflow and precipitation, and precipitation, which canwhich be consideredcan be considered an indication an indication of active of recharge active recharge from the from check the dam. check dam.

Figure 7. WaterWater level level in in the the check check dam dam reservoir, reservoir, water water levels levels in the in groundwater the groundwater Wells Wells 1 and 12, and check 2, checkdam inflow dam inflow (stream (stream discharge), discharge), and prec andipitation precipitation during during the 2014 the to 2014 2015 to season. 2015 season.

The uncertainty interval of the calculated Qr (0.37 million m3 to 36.61 million m3) seems quite The uncertainty interval of the calculated Q (0.37 million m3 to 36.61 million m3) seems quite large (Table 1). However, it should be noted thatr running the model with upper and lower limits large (Table1). However, it should be noted that running the model with upper and lower limits (Equations (7) and (8)) is a maximalist interpretation of the errors. This approach assumes that all the water balance components are either at their upper or lower limits, which means that all errors in

Water 2017, 9, 813 12 of 16

(Equations (7) and (8)) is a maximalist interpretation of the errors. This approach assumes that all the water balance components are either at their upper or lower limits, which means that all errors in outflow, inflow, and evaporation affect simultaneously, at their maximum, the change in storage and are therefore reflected in the computed recharge. Nevertheless, it is remarkable to see such a great effect of the accumulated errors on the recharge for a water balance calculation.

3.4. Sediment Build-up in the Check Dam Reservoir The average dry bulk density of the samples collected in 2013 was 1.1 g cm−3 (minimum: 0.9 g cm−3, maximum: 1.2 g cm−3, standard deviation: 0.1 g cm−3) and, for the samples collected in 2015, was 1.1 g cm−3 (minimum: 0.8 g cm−3, maximum: 1.4 g cm−3, standard deviation: 0.1 g cm−3). There was no significant variation in the bulk density values between the samples collected from different depths and in diferent years. However, the surface samples from the two locations closest to the check dam inlet had slightly higher bulk density values (1.2–1.4 g cm−3) than the average for both years. This is because these samples were sandier than the others. This can be due to the fact that coarser sediments are deposited earlier than finer sediments when the water flow velocity is reduced by the check dam [42]. The average depth of the sediment at the sample locations in 2013 was 21.6 cm (maximum: 35 cm, minimum: 5 cm and standard deviation: 8 cm) and, in 2015, was 22 cm (maximum: 48 cm, minimum: 5 cm, standard deviation: 10.8 cm). From the bulk density measurements (average 1.1 g cm−3) and the elevation differences (average 21.6 cm between 2011 and 2013 and 22 cm between 2013 and 2015), the total sediment build-up in the check dam reservoir was estimated to be 2640 tons for the years 2011 to 2012 and 2012 to 2013 and 2770 tons for the years 2013 to 2014 and 2014 to 2015, showing no significant difference. However, the total modelled streamflow into the reservoir was three times more for the former (Table1). The season from 2011 to 2012 had above-average inflow to the reservoir, and the 2013 to 2014 season had almost no inflow. Figure8 shows the discharge into the reservoir per day and cumulative frequency of each day over the two-year periods of 2011 to 2013 and 2013 to 2015. It can be seen from Figure8 that the years 2011 to 2013 had more days with higher discharge compared with the years 2013 to 2015. The years 2011 to 2013 had ten days with high flow (occurring less than 4% of the time) and none above 1.5 million m3 day−1, and the years 2013 to 2015 had only five days with high flow, one of which was an extreme event (2.4 million m3 day−1 on 6 January 2015). These results indicate that the high flow events, occurring less than 4% of the time in our case, can carry and build up most, if not all, of the sediment. Visual assessment of the high-flow events also supports this deduction as the of the stream water for these events was significantly higher. Moreover, events occurring less than 4% of the time constituted 30% of the total inflow in 2011 to 2013 and 40% in 2013 to 2015. The importance of high-flow events for , along Mediterranean rivers comparable to Peristerona, has been reported by many authors [43–46]. Rovira and Batalla [44] studied the temporal distribution of suspended sediment transport in a Mediterranean basin in north-eastern Spain and concluded that 90% of the total sediment flow was carried by flood events, which occur 30% of the time. Vericat and Batalla [45] reported, for a watershed in southern Pyrenees, that 74% of the total sediment load was carried by flood events that occur 4% of the time. Achite and Ouillon [46] investigated sediment transport in a mountainous watershed in Algeria for 40 years and concluded that most of the sediment was carried by the 10 to 15 highest daily discharges over a year. Djuma et al. [18] computed the area-specific sediment yield for 2011 to 2013 as 1 tons hectare−1 year−1 for the Peristerona watershed, assuming a 15% sediment trapping efficiency of the check dam. This efficiency was based on the ratio of the watershed area (km2) and the capacity of the check dam (m3)[47] and ignores the amount of inflowing water. Assuming that the suspended sediment concentration in the water outflow is the same as that of the inflow, the trapping efficiency can be estimated to be around 30%, as the total water outflow from the check dam was 70% of the total water inflow (Table1). Conversely, assuming that all the sediment is carried by extreme events (upper 4%) Water 2017, 9, 813 13 of 16 then the trapping efficiency can be estimated to be around 6%, as the total outflow from the check dam Water 2017, 9, 813 13 of 16 was 94% of the total water inflow for these events.

FigureFigure 8. 8. DischargeDischarge into into the the reservoir reservoir per per day day and and cumula cumulativetive frequency frequency of of each each day day over over a a two-year two-year periodperiod for for 2011 2011 to to 2013 2013 and and 2013 2013 to to 2015. 2015.

4.4. Conclusions Conclusions WeWe found that a check damdam withwith aa reservoirreservoir capacity capacity of of around around 25,000 25,000 m m3 on3 on an an ephemeral ephemeral river river of ofa 105-kma 105-km2 watershed2 watershed in in Cyprus Cyprus was was able able to rechargeto recharge 2.1 2.1 times times more more groundwater groundwater than than an 11-km-long an 11-km- longriver river transect transect upstream upstream of the of check the check dam. dam. This This conclusion conclusion is an is indication an indication of the of usefulness the usefulness of such of suchstructures structures for the for replenishment the replenishment of groundwater of groundwater resources resources in arid andin arid semi-arid and semi-arid regions. Weregions. estimated We estimatedthe recharge the through recharge water through balance water calculations, balance calcul andations, we stressed and we the stressed high uncertainties the high uncertainties of the results. of theThis results. is mainly This due is mainly to uncertainties due to uncertainties in the inflow, in whichthe inflow, affect which the change affectin the storage change and in arestorage reflected and aredirectly reflected in the directly computed in the recharge. computed Continuous recharge. Co flowntinuous measurements flow measurements can help to can reduce help theto reduce inflow theuncertainties inflow uncertainties and better and evaluate better the evaluate performance the performance of the check of dam.the check dam. OurOur computations computations indicated indicated that that 70% 70% of of the the water water flowing flowing into into the the check check dam dam continued downstream.downstream. The The distribution distribution of the of daily the daily flow data flow indicated data indicated that the that flow the events flow occurring events occurring less than 4%less of than the 4%time of constitute the time constitutemore than more 30% thanof the 30% total of check-dam the total check-dam inflow, and inflow, 94% of and this 94% inflow of this is dischargedinflow is discharged out of the check out of dam. the check Thus, dam. due to Thus, the limited due to capacity the limited of the capacity check ofdam the and check the damextreme and dischargethe extreme during discharge these events, during a these large events,part of athe large potential part ofgroundwater the potential recharge groundwater is missed. recharge Further is researchmissed. Furtheris needed research on the is neededcheck dams on the downstre check damsam from downstream the studied from check the studied dam check(e.g., flow dam measurements(e.g., flow measurements and water balanceand water calculations) balance calculations) to evaluate the to usefulness evaluate the of usefulnessthis series of of structures. this series of structures.To better evaluate the sedimentation rate and its effects on recharge, the check-dam sediment trappingTo better efficiency evaluate should the be sedimentation evaluated per rate flow and event its effectswith total on recharge,water inflow, the check-damcheck-dam sedimentcapacity, andtrapping turbidity efficiency sensors should with continuous be evaluated measurements, per flow event in withaddition total to water inflow, tests check-dam at the reservoir. capacity, Theand evaluation turbidity sensorsof sedimentation with continuous at the measurements,downstream check in addition dams could to infiltration also support tests atthese the measurements.reservoir. The evaluationErosion prevention of sedimentation techniques at the (e.g., downstream afforestation, check the damsrevitalization could also or supportmaintenance these ofmeasurements. abandoned agricultural Erosion prevention dry-stone techniques terraces, (e.g., prev afforestation,ention of road the erosion) revitalization can be or maintenanceapplied at the of watershedabandoned level agricultural to reduce dry-stone the sedimentation terraces, prevention in the check-dam of road erosion) reservoir can area. be applied These techniques at the watershed have thelevel added to reduce advantage the sedimentation of not only reducing in the check-dam soil erosio reservoirn and keeping area. Thesesoil fertile techniques but also have increasing the added the groundwateradvantage of notrecharge only reducing by limiting soil the erosion sediment and keeping build-up. soil fertile but also increasing the groundwater recharge by limiting the sediment build-up. Acknowledgments: We would like to thank our colleague Marina Faka for leading the topographic survey. We would also like to thank Christos Christofi from the Cyprus Geological Survey Department, Gerald Dörflinger from the Water Development Department, Filippos Tymvios from the Department of Meteorology, and their colleagues for providing data. This research received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 603498 (RECARE project—Preventing and Remediating degradation of soils in Europe through Land Care).

Author Contributions: Hakan Djuma designed the methodology, collected and analysed the field data, and prepared the manuscript. Adriana Bruggeman and Corrado Camera supervised the study and helped with the

Water 2017, 9, 813 14 of 16

Acknowledgments: We would like to thank our colleague Marina Faka for leading the topographic survey. We would also like to thank Christos Christofi from the Cyprus Geological Survey Department, Gerald Dörflinger from the Water Development Department, Filippos Tymvios from the Department of Meteorology, and their colleagues for providing data. This research received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 603498 (RECARE project—Preventing and Remediating degradation of soils in Europe through Land Care). Author Contributions: Hakan Djuma designed the methodology, collected and analysed the field data, and prepared the manuscript. Adriana Bruggeman and Corrado Camera supervised the study and helped with the field data collection and manuscript preparation. Marinos Eliades helped with the design and collection of the field data and reviewed the manuscript. Konstantinos Kostarelos provided advice on the methodology and helped with preparation of the manuscript. Conflicts of Interest: The authors declare no conflicts of interest.

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