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The spatial characteristics and patterns of snow accumulation and ablation inform the amount of water stored and subsequently available for runoff and the timing of snowmelt. This paper characterizes the snow accumulation phase to investigate the spatiotemporal snow water equivalent (SWE) distribution by fitting a function to the trajectory plot of the standard deviation versus mean SWE across a domain. Data were used from 90 snow stations for a 34-year period across the Southern Rocky Mountains in the western United States. The stations were divided into sub-sets based on elevation, latitude, and the mean annual maximum SWE. The best function was a linear fit, excluding the first 35 mm of SWE. There was less variability with SWE data compared to snow depth data. The trajectory of the accumulation phase was consistent for most years, with limited correlation to the amount of accumulation. These trajectories are more similar for the northern portion of the domain and for below average snow years. This work could inform where to locate new stations, or be applied to other earth system variables.

Lack of knowledge about freshwater use in ports of tourist destinations hinders accurate assessment of water availability and water planning. In this study, freshwater use in the Port of Palma (Spain) is analyzed by sector (commercial, mixed, navy and recreational) for the period 2007–2018. This study shows the dynamics of consumption and evaluates the effects of increased cruise tourism from 2007 to 2018 in the port. Water data supplied by the Port Authority of the Balearic Islands for each sector, together with water volumes recharged by ships, allow a detailed analysis of the water used by merchants and cruise lines. Results reveal a significant increase in freshwater withdrawals by cruise ships in the Port of Palma in the last ten years, closely related to the boom of cruise activity. Water use and recharge by cruise ships increased in both the high and low tourist seasons. Homeport cruises have a significant effect on the increase of freshwater withdrawals, as each homeport cruise ship recharged a mean volume of 628 m3 per mooring. This paper proposes a water withdrawal indicator of liters loaded per passenger at the port. Given the current lack of restriction on the number of cruise ships per day docking in the Port of Palma, cruise activity may well become a threat to water availability during drought episodes and another environmental cost to add to the already questioned cruise tourism activity of the island.

The Balearic Islands are a major Mediterranean tourist destination that features one of the greatest swimming pool densities within Europe. In this paper, standard meteorological data were combined with a diachronic swimming pool inventory to estimate water evaporation from swimming pools over the Balearic archipelago. Evaporation was estimated using an empirical equation designed for open-water surfaces. Results revealed a 32% increase in swimming pools’ water use by 2015. Evaporation from swimming pools added 9.6 L of water to touristic consumption per guest night and person, and represented 4.9% of the total urban water consumption. In 2015, almost 5 hm3 (5 billion L) were lost from pools across the Balearic Islands. In several densely urbanized areas, evaporative water loss from pools exceeded four million litres per square kilometre and year. The water needed to refill the total of 62,599 swimming pools and to counteract evaporative water loss is equivalent to 1.2 pools per year. Swimming pools have rapidly proliferated across the islands. We have expounded on this development in view of much-needed responsible water management across the islands.

We use high quality climate data from ground meteorological stations in the Iberian Peninsula (IP) and robust drought indices to confirm that drought severity has increased in the past five decades, as a consequence of greater atmospheric evaporative demand resulting from temperature rise. Increased drought severity is independent of the model used to quantify the reference evapotranspiration. We have also focused on drought impacts to drought-sensitive systems, such as river discharge, by analyzing streamflow data for 287 rivers in the IP, and found that hydrological drought frequency and severity have also increased in the past five decades in natural, regulated and highly regulated basins. Recent positive trend in the atmospheric water demand has had a direct influence on the temporal evolution of streamflows, clearly identified during the warm season, in which higher evapotranspiration rates are recorded. This pattern of increase in evaporative demand and greater drought severity is probably applicable to other semiarid regions of the world, including other Mediterranean areas, the Sahel, southern Australia and South Africa, and can be expected to increasingly compromise water supplies and cause political, social and economic tensions among regions in the near future.

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En este trabajo se analizan los cambios ocurridos en la evolución temporal de los caudales y del régimen hídrico en la cabecera fluvial del río Duero y su relación con la tendencia de las temperaturas, las precipitaciones y la superficie ocupada por el bosque. Los resultados muestran un decrecimiento significativo en las aportaciones hídricas anuales debido a la marcada reducción de las aportaciones entre los meses de febrero y septiembre, con un aumento sustancial del número de días al año con un caudal inferior a la tercera parte del caudal diário medio anual (“régimen de aguas bajas”). La buena correlación entre precipitaciones y aportaciones anuales (R = 0,72, valor-p < 0,001) y la ausencia de tendencia alguna en el análisis de los residuales prueban que el moderado avance de la superficie forestal durante las últimas décadas de momento no es suficiente para influir de manera determinante en la reducción de las aportaciones registrada. No obstante, la falta de correspondência entre las tendencias mensuales de precipitaciones y aportaciones y la destacable subida de las temperaturas sugieren un aumento del consumo de agua por parte del bosque que muy probablemente afecte de forma claramente perceptible a las aportaciones anuales de la cuenca a corto-medio plazo. Finalmente, la disminución de las precipitaciones y los cambios ocurridos en su reparto intraanual han afectado al régimen del río, que há pasado de tener un máximo invernal de carácter pluvial a un régimen bimodal con un pico principal en invierno y otro secundario en primavera. Esta circunstancia sin duda debe considerarse en la gestión de los embalses situados aguas abajo.

La disponibilidad de recursos hídricos ha sido históricamente un factor limitante de desarrollo en los países de la cuenca mediterránea. Durante las últimas décadas la presión sobre la disponibilidad se ha acentuado debido a los cambios ambientales observados como resultado del desarrollo industrial. En este trabajo se analizan la evolución y variabilidad recientes (1961-2005) de los recursos hídricos superficiales –el caudal en los ríos– en una de las cuencas hidrográficas de mayor entidad de la Península Ibérica, y los factores ambientales responsables de su evolución. Los resultados del trabajo muestran un descenso notable y generalizado en los caudales en la región, acompañado de un cambio en los regímenes fluviales. La evolución del clima, con unas precipitaciones muy variables pero sin tendencias notables a largo plazo, y unas temperaturas en aumento, explica en parte, pero no en su totalidad, el descenso hidrológico. En las cabeceras fluviales se ha detectado un incremento significativo de la cubierta vegetal durante el periodo de estudio, el cual parece estar participando en gran medida en el descenso de caudales. Por otro lado, la regulación por medio de embalses está incrementando en la cuenca y con ello contribuyendo al cambio hidrológico en la región. Los resultados obtenidos ofrecen la base conceptual para proyectar la disponibilidad futura de los recursos hídricos en los escenarios de mayor escasez como consecuencia del cambio climático venidero.

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