Christophe Cudennec

A decade of Predictions in Ungauged Basins (PUB)—a review

Abstract The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23–25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community. Editor D. Koutsoyiannis Citation Hrachowitz, M., Savenije, H.H.G., Blöschl, G., McDonnell, J.J., Sivapalan, M., Pomeroy, J.W., Arheimer, B., Blume, T., Clark, M.P., Ehret, U., Fenicia, F., Freer, J.E., Gelfan, A., Gupta, H.V., Hughes, D.A., Hut, R.W., Montanari, A., Pande, S., Tetzlaff, D., Troch, P.A., Uhlenbrook, S., Wagener, T., Winsemius, H.C., Woods, R.A., Zehe, E., and Cudennec, C., 2013. A decade of Predictions in Ungauged Basins (PUB)—a review. Hydrological Sciences Journal, 58 (6), 1198–1255.

Panta Rhei-Everything Flows: Change in hydrology and society-The IAHS Scientific Decade 2013-2022

Abstract The new Scientific Decade 2013–2022 of IAHS, entitled “Panta Rhei—Everything Flows”, is dedicated to research activities on change in hydrology and society. The purpose of Panta Rhei is to reach an improved interpretation of the processes governing the water cycle by focusing on their changing dynamics in connection with rapidly changing human systems. The practical aim is to improve our capability to make predictions of water resources dynamics to support sustainable societal development in a changing environment. The concept implies a focus on hydrological systems as a changing interface between environment and society, whose dynamics are essential to determine water security, human safety and development, and to set priorities for environmental management. The Scientific Decade 2013–2022 will devise innovative theoretical blueprints for the representation of processes including change and will focus on advanced monitoring and data analysis techniques. Interdisciplinarity will be sought by increased efforts to connect with the socio-economic sciences and geosciences in general. This paper presents a summary of the Science Plan of Panta Rhei, its targets, research questions and expected outcomes. Editor Z.W. Kundzewicz Citation Montanari, A., Young, G., Savenije, H.H.G., Hughes, D., Wagener, T., Ren, L.L., Koutsoyiannis, D., Cudennec, C., Toth, E., Grimaldi, S., Blöschl, G., Sivapalan, M., Beven, K., Gupta, H., Hipsey, M., Schaefli, B., Arheimer, B., Boegh, E., Schymanski, S.J., Di Baldassarre, G., Yu, B., Hubert, P., Huang, Y., Schumann, A., Post, D., Srinivasan, V., Harman, C., Thompson, S., Rogger, M., Viglione, A., McMillan, H., Characklis, G., Pang, Z., and Belyaev, V., 2013. “Panta Rhei—Everything Flows”: Change in hydrology and society—The IAHS Scientific Decade 2013–2022. Hydrological Sciences Journal. 58 (6) 1256–1275.

Dryland hydrology in Mediterranean regions—a review

CHRISTOPHE CUDENNEC, CHRISTIAN LEDUC & DEMETRIS KOUTSOYIANNIS 1 INRA, Agrocampus Rennes, UMR 1069, SAS, F-35000 Rennes, France cudennec@agrocampus-rennes.fr 2 IRD, UMR G-EAU, Case MSE, BP 64501, 34394 Montpellier cedex 5, France leduc@ird.fr 3 Department of Water Resources, Faculty of Civil Engineering, National Technical University of Athens, Heroon Polytechneiou 5, GR 157 80 Zographou, Greece dk@itia.ntua.gr

Panta Rhei 2013–2015: global perspectives on hydrology, society and change

ABSTRACT In 2013, the International Association of Hydrological Sciences (IAHS) launched the hydrological decade 2013–2022 with the theme “Panta Rhei: Change in Hydrology and Society”. The decade recognizes the urgency of hydrological research to understand and predict the interactions of society and water, to support sustainable water resource use under changing climatic and environmental conditions. This paper reports on the first Panta Rhei biennium 2013–2015, providing a comprehensive resource that describes the scope and direction of Panta Rhei. We bring together the knowledge of all the Panta Rhei working groups, to summarize the most pressing research questions and how the hydrological community is progressing towards those goals. We draw out interconnections between different strands of research, and reflect on the need to take a global view on hydrology in the current era of human impacts and environmental change. Finally, we look back to the six driving science questions identified at the outset of Panta Rhei, to quantify progress towards those aims. Editor D. Koutsoyiannis; Associate editor not assigned

Accounting for sparsely observed rainfall space—time variability in a rainfall—runoff model of a semiarid Tunisian basin/Prise en compte d'observations peu denses de la variabilité spatiotemporelle de la pluie dans une modélisation pluie—débit d'un bassin semi-aride Tunisien

Abstract The management of water excesses and deficits is a major task in semiarid Mediterranean regions, where the variability of rainfall inputs is high at different time and space scales. Thus intense hydrometeorological events, which generate both potential resource and hazards, are of major interest. A simple method is proposed, with the example of the Skhira basin (192 km2) in central Tunisia, to account for the event space–time variability of rainfall in a rainfall–runoff model, in order to check its influence on the shape, magnitude and timing of resulting hydrographs. The transfer function used is a geomorphology-based unit hydrograph with an explicit territorial significance. Simulations made for highly variable events show the relevance of this method, seen as the first step of a downward approach, and its robustness with respect to the quality and the density of rainfall data.

Modeling Water Quality to Improve Agricultural Practices and Land Management in a Tunisian Catchment Using the Soil and Water Assessment Tool

Agriculture intensification has impaired water quality. In this study, the risk of pollution by nitrates was assessed by experimental monitoring, spatial integration of farm census, and modeling of water quality using the Soil and Water Assessment Tool (SWAT), version 2009, over the period of 1990 to 2006 for a catchment located northern Tunisia. Under a semiarid climate, the water quality is influenced by the predominating agriculture activities. The hydrological results are compared with the observed flows derived from measurements at the outlet of the Joumine watershed. Model performance showed good statistical agreements, with a Nash-Sutcliffe efficiency of 0.9 and a value of 0.92 after monthly calibration. The model predicted the timing of monthly peak flow values reasonably well. During the validation period, SWAT simulations were nearly as accurate, with Nash-Sutcliffe efficiency and values of 0.89 and 0.92, respectively. The model was used to simulate NO concentrations. The predicted NO concentration values were compared with in situ measured concentrations. The simulated and measured NO-N concentrations varied in the same range of 0 to 5 mg L at the E3 and E5 locations. The calibrated model was then used for simulating the impact of the best management practice scenarios to reduce NO loads to the river. The first set-up consisted of reducing the N fertilizer application by 20 and 100% from the current state. These two scenarios induced a reduction in NO loads by 22 and 72%, respectively. The second set-up consisted of using vegetation filter strips. The last scenario combined filter strips and a reduction of 20% in N fertilizer application. Results showed NO reduction rates of 20 and 36%, respectively. The SWAT model allowed managers to have several options to improve the water quality in the Joumine watershed.

Incorporating elevation in rainfall interpolation in Tunisia using geostatistical methods

Abstract This paper compares the performance of three geostatistical algorithms, which integrate elevation as an auxiliary variable: kriging with external drift (KED); kriging combined with regression, called regression kriging (RK) or kriging after detrending; and co-kriging (CK). These three methods differ by the way by in which the secondary information is introduced into the prediction procedure. They are applied to improve the prediction of the monthly average rainfall observations measured at 106 climatic stations in Tunisia over an area of 164 150 km2 using the elevation as the auxiliary variable. The experimental sample semivariograms, residual semivariograms and cross-variograms are constructed and fitted to estimate the rainfall levels and the estimation variance at the nodes of a square grid of 20 km × 20 km resolution and to develop corresponding contour maps. Contour diagrams for KED and RK were similar and exhibited a pattern corresponding more closely to local topographic features when (a) the network is sparse and (b) the rainfall–elevation correlation is poor, while CK showed a smooth zonal pattern. Smaller prediction variances are obtained for the RK algorithm. The cross-validation showed that the RMSE obtained for CK gave better results than for KED or RK. Editor D. Koutsoyiannis; Associate editor C. Onof Citation Feki, H., Slimani, M., and Cudennec, C., 2012. Incorporating elevation in rainfall interpolation in Tunisia using geostatistical methods. Hydrological Sciences Journal, 57 (7), 1294–1314.

Measurements and Observations in the XXI century (MOXXI): innovation and multi-disciplinarity to sense the hydrological cycle

ABSTRACT To promote the advancement of novel observation techniques that may lead to new sources of information to help better understand the hydrological cycle, the International Association of Hydrological Sciences (IAHS) established the Measurements and Observations in the XXI century (MOXXI) Working Group in July 2013. The group comprises a growing community of tech-enthusiastic hydrologists that design and develop their own sensing systems, adopt a multi-disciplinary perspective in tackling complex observations, often use low-cost equipment intended for other applications to build innovative sensors, or perform opportunistic measurements. This paper states the objectives of the group and reviews major advances carried out by MOXXI members toward the advancement of hydrological sciences. Challenges and opportunities are outlined to provide strategic guidance for advancement of measurement, and thus discovery.

Hydrological processes in macrocatchment water harvesting in the arid region of Tunisia: the traditional system of tabias/Processus hydrologiques au sein d’un aménagement de collecte des eaux dans la région aride tunisienne: le système traditionnel des tabias

Abstract Abstract In arid Tunisia, a tabia system is a traditional macrocatchment water harvesting system. It consists of a runoff area, which occupies two thirds of the slope and is traditionally used for grazing; and one to five cropped plots within U-shaped soil banks arranged in a cascade in the third downstream area. These ȁrun-onȁ areas accumulate and store the occasional runoff. Each soil bank is constructed with a discharge weir that allows modification of the flooded area and discharge of excess water towards downstream plots. Such a harvesting system, located in an area with 140 mm annual rainfall, was instrumented during four hydrological years (1995–1999) and 45 rainfall events were recorded. Eleven of these events gave a measurable inflow to at least one of the four plots. The observations showed that the traditional tabia system reduced total surface runoff from the catchment to essentially zero. The harvesting system significantly reduced peaks of surface runoff within the catchment, which also reduced erosion hazards. The cultivated area of about 5% of the total catchment could be supplied by a harvested water amount corresponding to about seven times the amount of each rainfall event larger than 20 mm.

Joint editorial – Fostering innovation and improving impact assessment for journal publications in hydrology

Editors of several journals in the field of hydrology met during the Assembly of the International Association of Hydrological Sciences—IAHS (within the Assembly of the International Union of Geodesy and Geophysics—IUGG) in Prague in June 2015. This event was a follow-up of a similar meeting held in July 2013 in Gothenburg (as reported by Bl€ oschl et al. [2014]). These meetings enable the group of editors to review the current status of the journals and the publication process, and share thoughts on future strategies. Journals were represented in the 2015 meeting through their editors, as shown in the list of authors. The main points on fostering innovation and improving impact assessment in journal publications in hydrology are communicated in this joint editorial published in the above journals. In the last few decades, the dominant practice of universities, governments and research funding organizations in assessing individuals or research proposals has been to use the number of papers published— sometimes separating those in high-impact journals—and number of citations as the main benchmarks, rather than true innovation (including new ideas, original methods, discovery and improved application of technology). This has resulted in consistently increasing pressure to publish in journals—the ‘‘publish-orperish’’ syndrome. In turn, this has transformed the publication industry (e.g., with the creation of numerous for-profit publication vehicles) as well as the peer review system per se. Specifically, with the plethora of journals, ‘‘peer review [. . .] is becoming a system that judges where work is published rather than whether the research is publishable (a ‘where rather than if’ process)’’ [Peres-Neto, 2015]. In the majority of journals represented in this editorial, submissions have dramatically increased. As a response, some of the journals have increased the rate of desk rejections, i.e., rapid rejections by the editor without sending the papers out for peer review, with the objective of reducing the pressure on the review system. It is the common agreement of all editors that the peer-review system is a key component of the publication process and essential for scientific progress of the community. Maintaining the highest quality of the peer-review process is thus crucial. However, the system has several weaknesses. Some of its critics have characterized it in strong language, e.g., as a ‘‘non-validated charade whose processes generate results little better than does chance’’ [Horrobin, 2001], and a recent editorial Comment in a medical journal [Horton, 2015] stated, ‘‘The case against science is straightforward: much of the scientific literature, perhaps half, may simply be untrue.’’ After completing a systematic survey of more than 1000 manuscripts submitted to three elite medical journals, Siler et al. [2015] concluded that ‘‘on the whole, there was value added in peer review,’’ even though ‘‘both errors of omission [rejecting a worthy article] and commission [publishing an unworthy article] were prominent.’’ Another symptom of the ‘‘publish-or-perish’’ syndrome is that research is becoming more fragmented. The same body of research is often split into a number of papers (a tactic sometimes referred to as ‘‘salami publishing’’). Such tactics may improve individuals’ citation counts and other bibliometric indices, but they also reduce their representativeness as indicators of scientific impact. The increasing number of publications, Correspondence to: A. Montanari, alberto.montanari@unibo.it Citation: Koutsoyiannis, D., G. Bl€ oschl, A. B ardossy, C. Cudennec, D. Hughes, A. Montanari, I. Neuweiler, and H. Savenije (2016), Joint editorial: Fostering innovation and improving impact assessment for journal publications in hydrology, Water Resour. Res., 52, 2399–2402, doi:10.1002/2016WR018895. Received 16 MAR 2016 Accepted 16 MAR 2016 Accepted article online 18 MAR 2016 Published online 29 APR 2016 VC 2016. American Geophysical Union. All Rights Reserved. KOUTSOYIANNIS ET AL. JOINT EDITORIAL 2399 Water Resources Research PUBLICATIONS