1 Fac ulty of Min ing, Ge ol ogy and Pe tro leum En gi neer ing, Uni ver sity of Zagreb, Pierottijeva 6, Zagreb, Croatia Mt. Medvednica is an inselberg in NW Croatia, which lies at the in ter sec tion be tween the Southeastern Alps, Northwestern Dinarides and Tisza Mega-Unit of the Pannonian Ba sin. Due to the Pliocene-Quaternary N-S di rected short en ing, Mt. Medvednica ex pe ri enced 1500-2000 m of dif fer en tial up lift and now ex poses pre-Neo gene and Neo gene tec tonic and stratigraphic units that are sur rounded by Pliocene-Quaternary sed i ments. This pa per eval u ates a set of quan ti ta tive morphometry meth ods used to iden tify tec toni cally ac tive ar eas within this re gion characterized by low-rate ac tive fold ing and fault ing dur ing the Pliocene-Quaternary. Our anal y sis em ployed ex trac tion of hypsometric curves, cal cu la tion of a hypsometric in te gral, asym me try fac tor, and sta tis ti cal pa ram e ters of lon gi tu di nal stream pro files along 36 drain age bas ins de lin eated from a 25 m res o lu tion DEM of Mt. Medvednica area. De spite lithological het er o ge ne ity of the study area, the morphometric pa ram e ters we ob tain are good in di ca tors for dis crim i nat ing tec toni cally ac tive from in ac tive ar eas. We in terpret that the most tec toni cally ac tive ar eas are lo cated at the SW cor ner and in the cen tral part of Mt. Medvednica, where they are likely re lated to the North Medvednica Bound ary Fault, and to the Kašina Fault, re spec tively. The lat ter di vides the range into dis tinct NE and SW mor pho log i cal and struc tural ar eas.

How should the success of river and floodplain restoration be assessed? What should we be restoring? We contend that the benchmark for restoration should be the river in its “natural,” that is, quasi‐equilibrium condition prior to deliberate modification. The pre‐modification condition of the river represents a quasi‐equilibrium state in which the river accommodates and adjusts to catchment water and sediment fluxes, whether in a pristine or modified catchment. The resulting assemblage of river landforms (e.g., bars, channels, backwaters) is in balance with the prevailing flood and sediment regime. Furthermore, equilibrium channel forms can adjust to changes in, for example, flood magnitude and frequency via for example, channel expansion or contraction. A restored river system is one that once was anthropogenically restricted, but now has regained capacity to adjust its form. River restoration needs understanding of the history and trajectory of pre‐modification channels, so that the “right” river type can be restored. To assess the scope and success of restoration, we propose using a natural character index (NCI). The NCI is the ratio between a parameter which describes the form and function of a river now (observed) and the same parameter measured at a point or points in time past (expected). Exemplar parameters include sinuosity, floodplain width, active channel width, bar area (at a given flow) and riparian vegetation. Measurement of these parameters utilizes a combination of aerial photos, archive maps and LiDAR‐derived terrain models, the availability of which necessarily limits and determines what parameters can be used in NCI assessment. LiDAR is a useful tool providing an opportunity to comprehend pre‐modification river and floodplain character. We illustrate the NCI concept and its potential for use in assessing restoration effects using examples from New Zealand, Spain and Croatia. The result is an index of use as a “first cut” preliminary assessment for river practitioners.

Morphometric analysis of Holocene pebbles from Sava River gravel in NW Croatia revealed shape distributions as observed along a 30 km long watercourse. Limestones, dolomites, and sandstones were identified as the major (>4%) and effusive magmatics in this alluvial aquifer system in Zagreb, with cherts and tuffs as minor pebble lithologies (up to 4%). Their distributions mainly indicate distant Alpine provenance for carbonate pebbles (limestone and dolomite) and local input for sandstones and minor lithotypes, laterally from the Samoborska Gora and Medvednica mountain. Carbonates are predominantly disc- and sphere-shaped, implying distant sources. Scattered distributions of pebble shapes (sphere, disc, blade, and rod) for sandstones and minor lithotypes possibly indicate multiple sources, some of them probably local. The tentatively interpreted “original sedimentary environments” for the main pebble lithotypes (calculated from their flatness ratios) possibly indicate that they are predominantly lake beach pebbles, followed by moraine and riverbed pebbles. However, these results should be strongly questioned.

River terraces and fl oodplains indicate channel-sediment dynamics and represent important landform features, which can be used to untangle the evolutionary history of climate and tectonic conditions in a certain area. With the availability of high-resolution topographic data, it has recently become feasible to apply GIS procedures for the identifi cation of these subtle landform features. In this study, the TerEx Toolbox, a GIS extension for semiautomatic terrace extraction was applied on the LiDAR based DEM of the Sava River, west of Zagreb in Croatia. The aim of this research was to compare results obtained by TerEx to the existing geological map from the 1970s, which shows sediments of the recent fl ow (routinely fl ooded area) and two abandoned Holocene river terraces in the study area. The TerEx output was validated using hillshaded DEM, a historical map of the study area, orthophoto imagery, topographic cross sections and fi eld investigations. TerEx has successfully extracted Holocene terraces and risers shown on the geological map but in some parts of the study area, their position and extent was diff erent. The presented study shows that results obtained by TerEx, in particular if used in combination with other data sources, can eff ectively focus fi eldwork and contribute to new unbiased interpretation of terrain morphology.

Morphometric analysis of Holocene pebbles from the Sava River gravels, in Zagreb alluvial aquifer system (NW Croatia), revealed distribution of their shapes along 30 km long observed watercourse. Limestones, dolomites and sandstones are determined as major (> 4%), and effusive magmatics, cherts and tuffs as minor lithotypes of the pebbles (up to 4%). Their distributions indicate mainly distant Alpine provenance for carbonate (limestones and dolomites) pebbles and local input for sandstones and minor lithotypes, laterally from the Samoborska gora and Medvednica Mts. Carbonates have predominately disc and sphere shapes, implying also their mainly distant sources. Scattered distributions of pebble shapes (sphere, disc, blade and rod) for sandstones and minor lithotypes indicate multiple sources, some of them probably local. Original sedimentary environments for main pebble lithotypes are tentatively interpreted from their flatness ratios, indicating predominant lake shore environments, followed by moraine and riverbed.